DEPARTMENT OF DEFENSE LAW OF WAR MANUAL (2015)

• taking to lifeboats.

13.4 ENEMY WARSHIPS

Enemy warships and naval and military auxiliaries are subject to attack, destruction, or

capture anywhere beyond neutral territory.

13.4.1 Character of Warships. A warship is generally understood to be a ship belonging

to the armed forces of a State bearing the external markings distinguishing the character and

nationality of such ships, under the command of an officer duly commissioned by the

government of that State and whose name appears in the appropriate service list of officers, and

manned by a crew that is under regular armed forces discipline.⁷⁷

Warships are generally understood to possess certain privileges and immunities from the

jurisdiction of other States.⁷⁸

13.4.2 Attacks Against Enemy Warships. In general, enemy warships are military

objectives.⁷⁹ However, warships that have surrendered or that are exempt vessels may not be

made the object of attack.⁸⁰

13.4.3 Captured Enemy Warships - No Prize Procedure. Prize procedures are not used

for captured enemy warships because their ownership vests immediately in the captor’s

⁷⁶ Trial of Helmuth von Ruchteschell, Outline of the Proceedings, IX U.N. LAW REPORTS 82 (British Military Court,

Hamburg, May 5-21, 1947) (“The captain of the Davisian stopped his engines, hoisted an answering pennant and

acknowledged the signal. In spite of this, the raider’s firing continued for 15 minutes, wounding 8 or 10 of the crew

of the Davisian, whilst they were trying to abandon ship [by taking to lifeboats].”).

⁷⁷ Convention on the High Seas, art. 8, Apr. 29, 1958, 450 UNTS 82, 86 (“1. Warships on the high seas have

complete immunity from the jurisdiction of any State other than the flag State. 2. For the purposes of these articles,

the term ‘warship’ means a ship belonging to the naval forces of a State and bearing the external marks

distinguishing warships of its nationality, under the command of an officer duly commissioned by the government

and whose name appears in the Navy List, and manned by a crew who are under regular naval discipline.”).

Consider LOS CONVENTION art. 29 (“For the purposes of this Convention, ‘warship’ means a ship belonging to the

armed forces of a State bearing the external marks distinguishing such ships of its nationality, under the command of

an officer duly commissioned by the government of the State and whose name appears in the appropriate service list

or its equivalent, and manned by a crew which is under regular armed forces discipline.”).

⁷⁸ See, e.g., The Schooner Exch. v. McFaddon, 11 U.S. 116, 144 (1812) (“But in all respects different is the situation

of a public armed ship. She constitutes a part of the military force of her nation; acts under the immediate and direct

command of the sovereign; is employed by him in national objects. He has many and powerful motives for

preventing those objects from being defeated by the interference of a foreign state. Such interference cannot take

place without affecting his power and his dignity. The implied license therefore under which such vessel enters a

friendly port, may reasonably be construed, and it seems to the Court, ought to be construed, as containing an

exemption from the jurisdiction of the sovereign, within whose territory she claims the rites of hospitality.”).

Consider LOS CONVENTION art. 95 (“Warships on the high seas have complete immunity from the jurisdiction of

any State other than the flag State.”).

⁷⁹ Refer to § 5.7.4 (Objects Categorically Recognized as Military Objectives).

⁸⁰ Refer to § 13.3.5 (Surrender by Enemy Vessels); § 13.6 (Enemy Vessels Exempt From Capture or Destruction).

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government by the fact of capture.⁸¹ As public movable property, warships are seizable as war

booty.⁸² Similarly, prize procedures are not used for captured enemy military aircraft.⁸³

13.5 ENEMY MERCHANT VESSELS

13.5.1 Capture of Enemy Merchant Vessels. Enemy merchant vessels may be captured

wherever located beyond neutral territory. Prior exercise of visit and search is not required,

provided positive determination of enemy status can be made by other means.⁸⁴

13.5.1.1 Captured Enemy Merchant Vessels - Notes on Terminology. A captured

neutral or enemy merchant vessel is called a prize.

13.5.1.2 Use of Prize Procedures to Complete Transfer of Title. Prize procedures

are usually used to complete the transfer of title of captured property, such as enemy merchant

ships.⁸⁵

13.5.1.3 Destruction of Captured Enemy Merchant Vessels. When military

circumstances preclude sending or taking in such vessel or aircraft for adjudication as an enemy

prize, it may be destroyed after all possible measures are taken to provide for the safety of

passengers and crew.⁸⁶ Documents and papers relating to the prize should be safeguarded and, if

⁸¹ 1955 NWIP 10-2 ¶503a(2) (“Enemy warships and military aircraft may be captured outside neutral jurisdiction.

Prize procedure is not used for such captured vessels and aircraft because their ownership immediately vests in the

captor’s government by the fact of capture.”).

⁸² Refer to § 5.17.3 (Enemy Movable Property on the Battlefield (War Booty)).

⁸³ Refer to § 14.5.3 (Capture of Aircraft and Goods on Board Aircraft).

⁸⁴ 2007 NWP 1-14M ¶8.6.2.1 (“Enemy merchant vessels and civil aircraft may be captured wherever located beyond

neutral territory. Prior exercise of visit and search is not required, provided positive determination of enemy status

can be made by other means.”).

⁸⁵ See, e.g., LAUTERPACHT, II OPPENHEIM’S INTERNATIONAL LAW 482 (§192) (“It has already been stated above that

the capture of a private enemy vessel has to be confirmed by a Prize Court, and that it is only through its

adjudication that the vessel becomes finally appropriated.”); Oakes v. United States, 174 U.S. 778, 786-87 (1899)

(“By the law of nations, recognized and administered in this country, when movable property in the hands of the

enemy, used, or intended to be used, for hostile purposes, is captured by land forces, the title passes to the captors as

soon as they have reduced the property to firm possession; but when such property is captured by naval forces, a

judicial decree of condemnation is usually necessary to complete the title of the captors.”).

⁸⁶ 2007 NWP 1-14M ¶8.6.2.1 (“When military circumstances preclude sending or taking in such vessel or aircraft

for adjudication as an enemy prize, it may be destroyed after all possible measures are taken to provide for the safety

of passengers and crew.”); 1955 NWIP 10-2 ¶503b(2) (“Enemy merchant vessels and aircraft which have been

captured may, in case of military necessity, be destroyed by the capturing officer when they cannot be sent or

escorted in for adjudication. Should the necessity for the destruction of an enemy prize arise, it is the duty of the

capturing officer to take all possible measures to provide for the safety of passengers and crew.”).

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practicable, the personal effects of passengers should be saved.⁸⁷ Every case of destruction of a

captured enemy prize should be reported promptly to higher command.⁸⁸

The destruction of neutral prizes involves similar procedures, but a more serious

responsibility.⁸⁹

13.5.2 Attack of Enemy Merchant Vessels. Enemy merchant vessels may be made the

object of attack, outside neutral territory, if they constitute a military objective.⁹⁰

In particular, enemy merchant vessels may be attacked and destroyed by warships, either

with or without prior warning, in any of the following circumstances:⁹¹

• persistently refusing to stop upon being duly summoned to do so;

• actively resisting visit and search or capture;

• sailing under convoy of enemy warships or enemy military aircraft;

• armed with systems or weapons beyond that required for self-defense against terrorist,

piracy, or like threats;

• if incorporated into, or assisting, the enemy’s military intelligence system;

• if acting in any capacity as a naval or military auxiliary to an enemy’s armed forces; or

• if otherwise integrated into the enemy’s war-fighting/war-sustaining effort such that a

belligerent warship’s compliance with the rules of the 1936 London Protocol would,

⁸⁷ 1955 NWIP 10-2 ¶503b(2) (“All documents and papers relating to an enemy prize should be saved. If practicable,

the personal effects of passengers should be saved.”).

⁸⁸ 1955 NWIP 10-2 ¶503b(2) (“Every case of destruction of an enemy prize should be reported promptly to higher

command.”).

⁸⁹ Refer to § 15.15.3 (Destruction of Neutral Prizes).

⁹⁰ Refer to § 5.7 (Military Objectives).

⁹¹ 2007 NWP 1-14M ¶8.6.2.2 (“Accordingly, enemy merchant vessels may be attacked and destroyed by surface

warships, either with or without prior warning, in any of the following circumstances: 1. Persistently refusing to

stop upon being duly summoned to do so 2. Actively resisting visit and search or capture 3. Sailing under convoy of

enemy warships or enemy military aircraft 4. If armed with systems or weapons beyond that required for self-

defense against terrorist, piracy, or like threats 5. If incorporated into, or assisting in any way, the intelligence

system of the enemy’s armed forces 6. If acting in any capacity as a naval or military auxiliary to an enemy’s armed

forces 7. If integrated into the enemy’s war-fighting/war-sustaining effort and compliance with the rules of the 1936

London Protocol would, under the circumstances of the specific encounter, subject the surface warship to imminent

danger or would otherwise preclude mission accomplishment.”); 1955 NWIP 10-2 ¶503b(3) (“Destruction of Enemy

Merchant Vessels Prior to Capture. Enemy merchant vessels may be attacked and destroyed, either with or without

prior warning, in any of the following circumstances: 1. Actively resisting visit and search or capture. 2. Refusing

to stop upon being duly summoned. 3. Sailing under convoy of enemy warships or enemy military aircraft. 4. If

armed, and there is reason to believe that such armament has been used, or is intended for use, offensively against an

enemy. 5. If incorporated into, or assisting in any way, the intelligence system of an enemy’s armed forces. 6. If

acting in any capacity as a naval or military auxiliary to an enemy’s armed forces.”).

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under the circumstances of the specific encounter, subject the warship to imminent

danger or would otherwise preclude mission accomplishment.

The 1936 London Protocol provides that “except in the case of persistent refusal to stop

on being duly summoned, or of active resistance to visit or search, a warship, whether surface

vessel or submarine, may not sink or render incapable of navigation a merchant vessel without

having first placed passengers, crew and ship’s papers in a place of safety.”⁹² Merchant vessels

in the sense of this rule, however, do not include merchant vessels that constitute military

objectives.⁹³

13.5.2.1 Attack of Civilian Passenger Vessels. If a civilian passenger vessel

constitutes a military objective and thus is liable to attack, any attack must comply with other

applicable rules related to attacks.⁹⁴

In particular, attacks against civilian passenger vessels engaged in passenger service must

comply with the requirement that the expected loss of life or injury to civilians, and damage to

civilian objects incidental to the attack, must not be excessive in relation to the concrete and

direct military advantage expected to be gained.⁹⁵

13.5.3 Detention of Personnel From Enemy Merchant Vessels. Officers and crews of

captured enemy merchant ships may be detained.⁹⁶ If detained, such persons are POWs.⁹⁷

⁹² Procès-Verbal Relating to the Rules of Submarine Warfare Set Forth in Part IV of the Treaty of London of April

22, 1930, Nov. 6, 1936, 173 LNTS 353, 357. See Treaty for the Limitation and Reduction of Naval Armament, art.

22, Apr. 22, 1930, 46 STAT. 2858, 2881-82 (“In particular, except in the case of persistent refusal to stop on being

duly summoned, or of active resistance to visit or search, a warship, whether surface vessel or submarine, may not

sink or render incapable of navigation a merchant vessel without having first placed passengers, crew and ship’s

papers in a place of safety. For this purpose the ship’s boats are not regarded as a place of safety unless the safety of

the passengers and crew is assured, in the existing sea and weather conditions, by the proximity of land, or the

presence of another vessel which is in a position to take them on board.”).

⁹³ Wolff Heintschel von Heinegg, The Law of Armed Conflict at Sea, in DIETER FLECK, THE HANDBOOK OF

HUMANITARIAN LAW IN ARMED CONFLICTS 428-29 (¶1025) (1999) (“The rules laid down in that document formed

part of the 1922 Washington Treaty and were reaffirmed by the 1930 London Conference. During that conference a

committee of legal experts presented a report in which the matter was clarified as follows: ‘The Committee wish to

place it on record that the expression ‘merchant vessel’, where it is employed in the declaration, is not to be

understood as including a merchant vessel which is at the moment participating in hostilities in such a manner as to

cause her to lose her right to the immunities of a merchant vessel.’ Whereas it remains unclear what is meant by

‘participating in hostilities’ it is obvious that merchant vessels are not in all circumstances protected by the 1936

London Protocol. This was confirmed by the judgment of the Nuremberg Tribunal. Hence, enemy merchant vessels

that, by their conduct, qualify as legitimate military objectives are not protected by the 1936 London Protocol and

may—as an exceptional measure—be attacked and sunk.”).

⁹⁴ Refer to § 5.5 (Rules on Conducting Assaults, Bombardments, and Other Attacks).

⁹⁵ Refer to § 5.12 (Proportionality in Conducting Attacks).

⁹⁶ 2007 NWP 1-14M ¶8.6.2.1 (“Officers and crews of captured enemy merchant ships and civilian aircraft may be

detained.”); 1955 NWIP 10-2 ¶512 (“The officers and crews of captured enemy merchant vessels and aircraft may

be made prisoners of war.”).

⁹⁷ Refer to § 4.16.2 (Merchant or Civil Crews - Detention).

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Other civilian enemy nationals on board such captured ships as private passengers are

subject to the discipline of the captor.⁹⁸ If detained, such persons must, at a minimum, be

afforded certain fundamental guarantees of humane treatment.⁹⁹

Nationals of a neutral State on board captured enemy merchant vessels should not be

detained unless they have participated in acts of hostility or resistance against the captor, or are

otherwise in the service of the enemy.¹⁰⁰

13.6 ENEMY VESSELS EXEMPT FROM CAPTURE OR DESTRUCTION

Certain classes of enemy vessels are exempt from capture or destruction, provided they

are innocently and solely employed in the activities that enjoy exempted status.

Exempt vessels may not be used for purposes outside their innocent role while taking

advantage of their harmless appearance. Warships may not be disguised as exempt vessels.¹⁰¹

13.6.1 Duties of Exempt Vessels. These specially protected vessels must not take part in

hostilities or assist the enemy’s military effort in any manner.

Such vessels and boats are subject to the regulations of a belligerent naval commander

operating in the area.¹⁰² They must not hamper the movement of combatants, must submit to

identification and inspection procedures, and may be ordered out of harm’s way. Refusal to

provide immediate identification upon demand is ordinarily sufficient legal justification for

capture or destruction.

13.6.2 Classes of Exempt Vessels. Specifically exempt vessels include: (1) cartel

vessels; (2) hospital ships; (3) vessels charged with religious, non-military scientific, or

philanthropic missions; (4) vessels granted safe conduct; and (5) small fishing and trade

vessels.¹⁰³

⁹⁸ 2007 NWP 1-14M ¶8.6.2.1 (“Other enemy nationals on board such captured ships and aircraft as private

passengers are subject to the discipline of the captor.”); 1955 NWIP 10-2 ¶512 (“Other enemy nationals on board

captured enemy merchant vessels and aircraft as private passengers are subject to the discipline of a captor.”).

⁹⁹ Refer to § 8.1.1 (Overview of Detention Rules in This Manual and the Scope of Chapter VIII).

¹⁰⁰ 2007 NWP 1-14M ¶8.6.2.1 (“Nationals of a neutral nation on board captured enemy merchant vessels and

civilian aircraft should not be detained unless they have participated in acts of hostility or resistance against the

captor or are otherwise in the service of the enemy.”); 1955 NWIP 10-2 ¶512 (“The nationals of a neutral state on

board captured enemy merchant vessels and aircraft as private passengers should not be made prisoners of war.”).

Refer to § 15.6.2 (Forfeiture of Protections of Neutral Status by a Neutral Person).

¹⁰¹ Refer to § 13.13 (Deception by Naval Forces, Including the Use of Enemy or Neutral Flags).

¹⁰² Refer to § 13.8 (Belligerent Control of the Immediate Area of Naval Operations).

¹⁰³ 1955 NWIP 10-2 ¶503c (“The following enemy vessels and aircraft, when innocently employed, are exempt from

destruction or capture: 1. Cartel vessels and aircraft, i.e., vessels and aircraft designated for and engaged in the

exchange of prisoners. 2. Properly designated hospital ships, medical transports, and medical aircraft. 3. Vessels

charged with religious, scientific, or philanthropic missions.

4. Vessels and aircraft guaranteed safe conduct by prior

arrangement between the belligerents. 5. Vessels and aircraft exempt by proclamation, operation plan, order, or

other directive.

6. Small costal (not deep-sea) fishing vessels and small boats engaged in local coastal trade and not

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13.6.2.1 Cartel Vessels. Vessels and aircraft designated for, and engaged in, the

exchange of POWs are privileged from capture.¹⁰⁴

13.6.2.2 Hospital Ships That Meet the Requirements of the GWS-Sea. Hospital

ships, including military hospital ships, commissioned civilian hospital ships, and authorized

neutral hospital ships, that meet the requirements of the GWS-Sea are exempt from capture.¹⁰⁵

Hospital ships do not forfeit their exempt status if they are armed for self-defense purposes or if

they possess or use communications equipment with encryption.

Hospital ships may be armed with defensive weapon systems, including when necessary

certain crew-served weapons, as a prudent anti-terrorism/force protection (AT/FP) measure to

defend against small boat attacks.¹⁰⁶ The 1949 Geneva Conventions do not directly address

weapons systems for hospital ships, but they do expressly provide for the arming of crew

members with small arms for the maintenance of order and for the self-defense of the crew or the

sick and wounded.¹⁰⁷ The arming of the ship with crew-served weapons for self-defense of the

ship is not prohibited and is consistent with the ship’s humanitarian purpose and the crew’s duty

to safeguard the wounded and sick.

The GWS-Sea provides that hospital ships may not use or possess “secret codes” as

means of communication; however, state practice has evolved to accept that modern

communications systems (e.g., satellite communications and video teleconference systems) and

taking part in hostilities. Such vessels and boats are subject to the regulations of a belligerent naval commander

operating in the area.”).

¹⁰⁴ See, e.g., The Brig “Betsey”, 49 Ct. Cl. 125, 132 (Ct. Cl. 1913) (“What is a cartel in warfare of the nations? An

agreement between belligerents for the exchange of prisoners. What is a cartel ship except a vessel of belligerents

duly commissioned for the carriage by sea of exchanged prisoners from enemy country to their own country or for

the carriage of official communications to and from enemies?”); The Adula, 176 U.S. 361, 379-80 (1900) (“While

the mission of the Adula was not an unfriendly one to this Government, she was not a cartel ship, privileged from

capture as such, but one employed in a commercial enterprise for the personal profit of the charterer, and only

secondarily, if at all, for the purpose of humanity.”); Crawford v. The William Penn., 6 F. Cas. 778, 780-81

(C.C.D.N.J. 1815) (“What is the character of a cartel vessel, and of the persons concerned in her navigation? The

flag of truce which she carries, throws over her and them the mantle of peace. She is, pro hac vice, a neutral

licensed vessel; and all persons concerned in her navigation, upon the particular service in which both belligerents

have employed her, are neutral, in respect to both, and under the protection of both. She cannot carry on commerce

under the protection of her flag, because this was not the business for which she was employed, and for which the

immunities of that flag were granted to her. She is engaged in a special service, to carry prisoners from one place to

another; and, whilst so engaged, she is under the protection of both belligerents, in relation to every act necessarily

connected with that service.”).

¹⁰⁵ Refer to § 7.12.1.1 (Military Hospital Ships); § 7.12.1.2 (Commissioned Civilian Hospital Ships); § 7.12.1.3

(Authorized Neutral Civilian Hospital Ships).

¹⁰⁶ Refer to § 7.12.6.2 (Conditions That Do Not Deprive Hospital Ships and Sick-Bays of Vessels of Their

Protection).

¹⁰⁷ Refer to § 7.12.6.3 (Arming of Hospital Ships and Equipping Them With Defensive Devices).

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navigational technology (e.g., global positioning systems) require encryption.¹⁰⁸ Such systems

must not be used for military purposes or in any way that is harmful to an adversary.¹⁰⁹

13.6.2.3 Vessels Charged With Religious, Nonmilitary Scientific, or Philanthropic

Missions. Vessels charged with religious, nonmilitary scientific, or philanthropic missions are

exempt from capture.¹¹⁰ Vessels engaged in the collection of scientific data of potential military

application, however, would not be included within this exemption.

13.6.2.4 Vessels Granted Safe Conduct. Vessels and aircraft guaranteed safe

conduct by prior arrangement between the belligerents are exempt from capture.¹¹¹

13.6.2.5 Small Coastal Fishing Vessels and Small Boats Engaged in Local

Coastal Trade. Small coastal (not deep-sea) fishing vessels and small boats engaged in local

coastal trade are exempt from capture.¹¹²

13.7 SUBMARINE WARFARE

13.7.1 General Principle - Same Rules Applicable to Both Submarine and Surface

Warships. Submarine warships must comply with the same law of war rules that apply to

surface warships.¹¹³ For example, in their action with regard to merchant ships, submarines must

conform to the law of war rules to which surface vessels are subject.¹¹⁴ In general, submarines

must provide for the safety of passengers, crew, and ship’s papers before destruction of an

¹⁰⁸ Refer to § 7.12.2.7 (Use of Secret Codes for Communication).

¹⁰⁹ Refer to § 7.12.2.2 (No Use for Military Purposes); § 7.10.3.1 (Acts Harmful to the Enemy).

¹¹⁰ HAGUE XI art. 4 (“Vessels charged with religious, scientific, or philanthropic missions are likewise exempt from

capture.”).

¹¹¹ Refer to § 12.6.3 (Safe Conduct).

¹¹² HAGUE XI art. 3 (“Vessels used exclusively for fishing along the coast or small boats employed in local trade are

exempt from capture, as well as their appliances, rigging, tackle, and cargo. They cease to be exempt as soon as

they take any part whatever in hostilities. The Contracting Powers agree not to take advantage of the harmless

character of the said vessels in order to use them for military purposes while preserving their peaceful appearance.”);

The Paquete Habana, 175 U.S. 677, 708 (1900) (“This review of the precedents and authorities on the subject

appears to us abundantly to demonstrate that at the present day, by the general consent of the civilized nations of the

world, and independently of any express treaty or other public act, it is an established rule of international law,

founded on considerations of humanity to a poor and industrious order of men, and of the mutual convenience of

belligerent States, that coast fishing vessels, with their implements and supplies, cargoes and crews, unarmed, and

honestly pursuing their peaceful calling of catching and bringing in fresh fish, are exempt from capture as prize of

war. The exemption, of course, does not apply to coast fishermen or their vessels, if employed for a warlike

purpose, or in such a way as to give aid or information to the enemy; nor when military or naval operations create a

necessity to which all private interests must give way. Nor has the exemption been extended to ships or vessels

employed on the high sea in taking whales or seals, or cod or other fish which are not brought fresh to market, but

are salted or otherwise cured and made a regular article of commerce.”).

¹¹³ 2007 NWP 1-14M ¶8.7 (“The law of armed conflict imposes essentially the same rules on submarines as apply to

surface warships.”); 1997 NWP 9 ¶8.3 (same); 1989 NWP 9 ¶8.3 (same).

¹¹⁴ Treaty for the Limitation and Reduction of Naval Armament, art. 22, Apr. 22, 1930, 46 STAT. 2858, 2881 (“In

their action with regard to merchant ships, submarines must conform to the rules of International Law to which

surface vessels are subject.”). Consider Procès-Verbal Relating to the Rules of Submarine Warfare Set Forth in Part

IV of the Treaty of London of April 22, 1930, Nov. 6, 1936, 173 LNTS 353, 357 (same).

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enemy merchant vessel.¹¹⁵ However, the same exceptions to this rule that permit surface ships to

attack enemy merchant vessels that are military objectives also permit submarines to conduct

such attacks.¹¹⁶

13.7.2 Different Application of Law of War Rules in the Context of Submarine Warfare.

Although submarines must comply with the same law of war rules as surface ships, a law of war

rule may apply differently in the context of submarine warfare because of the different

circumstances of submarine warfare as compared to surface warfare.

For example, like surface warships, submarine warships also have an obligation to search

for and collect the shipwrecked, wounded, and sick after an engagement.¹¹⁷ This obligation,

however, is subject to certain practical limitations, and the practical limitations faced by

submarines may be different than those faced by surface vessels.¹¹⁸ For example, although a

surface warship might be able to take on board survivors after an engagement, a submarine may

have limited passenger carrying capabilities. Thus, it may be necessary to rely on other

measures (e.g., such as passing the location of possible survivors to a surface ship, aircraft, or

shore facility capable of rendering assistance) to comply with the law of war obligation.¹¹⁹

13.8 BELLIGERENT CONTROL OF THE IMMEDIATE AREA OF NAVAL OPERATIONS

13.8.1 Belligerent Right to Establish Special Restrictions in the Immediate Area of Naval

Operations. Within the immediate area or vicinity of naval operations, to ensure proper battle

space management and self-defense objectives, a belligerent State may establish special

restrictions upon the activities of neutral vessels and aircraft, and may prohibit altogether such

vessels and aircraft from entering the area.¹²⁰

¹¹⁵ Refer to § 13.5.1.3 (Destruction of Captured Enemy Merchant Vessels).

¹¹⁶ Refer to § 13.5.2 (Attack of Enemy Merchant Vessels).

¹¹⁷ Refer to § 7.4.1 (GWS-Sea Obligation Regarding the Search, Collection, and Affirmative Protection of the

Wounded, Sick, Shipwrecked, and Dead).

¹¹⁸ Refer to § 7.4.4 (Practical Limitations on the Obligation to Search for, Collect, and Take Measures to Protect the

Wounded, Sick, and Shipwrecked).

¹¹⁹ Affidavit subscribed by Chester W. Nimitz, Fleet Admiral, Chief of Naval Operations, U.S. Navy from Joseph L.

Broderick, Lieutenant Commander, U.S. Naval Reserve, of the International Law Section, Office of the Judge

Advocate General, Navy Department (11 May 1946), in XVII TRIAL OF THE MAJOR WAR CRIMINALS BEFORE THE

IMT 379-80 (“13. Q: ‘Were, by order or on general principles, the U.S. submarines prohibited from carrying out

rescue measures toward passengers and crews of ships sunk without warning in those cases where by doing so the

safety of their own boat was endangered?’ ‘A: ‘On general principles, the U.S. submarines did not rescue enemy

survivors if undue additional hazard to the submarine resulted or the submarine would thereby be prevented from

accomplishing its further mission. U.S. submarines were limited in rescue measures by small passenger-carrying

facilities combined with the known desperate and suicidal character of the enemy. Therefore, it was unsafe to pick

up many survivors. Frequently survivors were given rubber boats and/or provisions. Almost invariably survivors

did not come aboard the submarine voluntarily, and it was necessary to take them prisoner by force.’”).

¹²⁰ 2007 NWP 1-14M ¶7.8 (“Within the immediate area or vicinity of naval operations, to ensure proper battle space

management and self-defense objectives, a belligerent may establish special restrictions upon the activities of neutral

vessels and aircraft and may prohibit altogether such vessels and aircraft from entering the area.”); 1955 NWIP

¶430b (“Within the immediate area or vicinity of naval operations, a belligerent may establish special restrictions

(see, for example, paragraph 520a) upon the activities of neutral vessels and aircraft and may prohibit altogether

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The immediate area or vicinity of naval operations is that area within which hostilities are

taking place, or belligerent State forces are actually operating.¹²¹

Belligerent State control over neutral vessels and aircraft within the immediate area of

naval operations is based upon a belligerent State’s right to ensure the security of its forces and

its right to conduct hostilities without interference from neutrals.¹²²

A belligerent State may not purport to deny access to neutral States, or to close an

international strait to neutral shipping, pursuant to this authority unless another route of similar

convenience remains open to neutral traffic.¹²³

13.8.2 Belligerent Right to Control Communication of Neutral Merchant Vessels or

Aircraft at Sea. A belligerent warship may exercise control over the communications of any

neutral merchant vessel or civil aircraft whose presence in the immediate vicinity of naval

operations might otherwise endanger or jeopardize those operations.¹²⁴

A neutral merchant ship or civil aircraft within that area that fails to conform to a

belligerent warship’s directions concerning communications may thereby assume enemy

character and risk being fired upon or captured.¹²⁵ Any transmission to an opposing belligerent

such vessels and aircraft from entering the area.”); 2006 AUSTRALIAN MANUAL ¶6.16 (“Within the immediate area

or vicinity of naval operations, a belligerent may establish special restrictions upon the activities of neutral vessels

and aircraft and may prohibit altogether such vessels and aircraft from entering the area.”); 2004 UK MANUAL

¶13.80 ( “Nothing in paragraphs 13.65 to 13.79 [on blockades and security zones] should be deemed to derogate

from the customary belligerent right to control neutral vessels and aircraft in the immediate vicinity of naval

operations.”).

¹²¹ 2007 NWP 1-14M ¶7.8 (“The immediate area or vicinity of naval operations is that area within which hostilities

are taking place or belligerent forces are actually operating.”); 1997 NWP 9 ¶7.8 (same); 1989 NWP 9 ¶7.8

(substantially similar); TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 300 (“It should be emphasized, though,

that the immediate area of naval operations refers to an area within which naval hostilities are taking place or within

which belligerent forces are actually operating.”).

¹²² TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 301 (“The claim to control neutral vessels and aircraft

within the immediate vicinity of operating forces is essentially a limited and transient one and is based not only upon

the right of a belligerent to insure the security of his forces but upon the right to attack and to defend himself without

interference from neutrals.”).

¹²³ 2007 NWP 1-14M ¶7.8 (“A belligerent may not, however, purport to deny access to neutral nations, or to close

an international strait to neutral shipping, pursuant to this authority unless another route of similar convenience

remains open to neutral traffic.”); 1997 NWP 9 ¶7.8 (same); 1989 NWP 9 ¶7.8 (same). Compare § 13.10.2.5

(Limitations on the Scope of the Blockade).

¹²⁴ 2007 NWP 1-14M ¶7.8 (“The commanding officer of a belligerent warship may exercise control over the

communication of any neutral merchant vessel or civil aircraft whose presence in the immediate area of naval

operations might otherwise endanger or jeopardize those operations.”); 1955 NWIP 10-2 ¶520a (“Within the

immediate vicinity of his forces, a belligerent commanding officer may exercise control over the communications of

any neutral merchant vessel or aircraft whose presence might otherwise endanger the success of the operations.”);

2006 AUSTRALIAN MANUAL ¶6.17 (“Within the immediate area or vicinity of naval operations, a commanding

officer of a belligerent warship may exercise control over the communications of any neutral merchant vessel or

aircraft whose presence might otherwise endanger the success of the belligerent operation.”).

¹²⁵ 2007 NWP 1-14M ¶7.8 (“A neutral merchant ship or civil aircraft within that area that fails to conform to a

belligerent’s directions concerning communications may thereby assume enemy character and risk being fired upon

or captured.”); 1955 NWIP 10-2 ¶430b (“Neutral vessels and aircraft which fail to comply with a belligerent’s

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State of information concerning military operations or military forces is inconsistent with the

neutral State’s duties of abstention and impartiality, and renders the neutral State’s vessel or

aircraft making such a communication liable to capture or destruction.¹²⁶

Legitimate distress communications should be permitted to the extent that the success of

the operation is not prejudiced thereby.¹²⁷

13.9 MARITIME AND AIRSPACE ZONES: EXCLUSION, WAR, OPERATIONAL, WARNING, AND

SAFETY

Belligerent States may establish various maritime and airspace zones during armed

conflict. The legal rules that apply to the establishment and enforcement of a zone may depend

on the function of the zone and, in particular, whether additional belligerent rights are asserted as

a consequence of vessels entering the zone.

Neutral or non-belligerent States have established such zones.¹²⁸

13.9.1 Authority to Establish Zones. The authority necessary to establish a zone may

depend on the location of the zone and the belligerent rights that are asserted as a consequence of

vessels entering the zone.

The establishment of a zone in a State’s waters may rely on its sovereignty over those

waters.¹²⁹ Similarly, the establishment of a zone in a State’s airspace may rely on its sovereignty

orders expose themselves to the risk of being fired upon. Such vessels and aircraft are also liable to capture (see

subparagraph 503d7).”).

¹²⁶ 2007 NWP 1-14M ¶7.8 (“Any transmission to an opposing belligerent of information concerning military

operations or military forces is inconsistent with the neutral duties of abstention and impartiality and renders the

neutral vessel or aircraft liable to capture or destruction.”). Consider Commission of Jurists to Consider and Report

Upon the Revision of the Rules of Warfare, General Report, Part I: Rules for the Control of Radio in Time of War,

art. 6, Feb. 19, 1923, reprinted in 32 AJIL SUPPLEMENT: OFFICIAL DOCUMENTS 2, 7-8 (1938) (“1. The transmission

by radio by a vessel or an aircraft, whether enemy or neutral, when on or over the high seas of military intelligence

for the immediate use of a belligerent is to be deemed a hostile act and will render the vessel or aircraft liable to be

fired upon. 2. A neutral vessel or neutral aircraft which transmits when on or over the high seas information

destined for a belligerent concerning military operations or military forces shall be liable to capture. The prize court

may condemn the vessel or aircraft if it considers that the circumstances justify condemnation.”).

¹²⁷ 2007 NWP 1-14M ¶7.8 (“Legitimate distress communications should be permitted to the extent that the success

of the operation is not prejudiced thereby.”); 1955 NWIP 10-2 ¶520a (“Legitimate distress communications by

neutral vessels and aircraft should be permitted if they do not prejudice the success of such operations.”).

¹²⁸ For example, The Nyon Arrangement Between the United Kingdom of Great Britain and Northern Ireland,

Bulgaria, Egypt, France, Greece, Roumania, Turkey, the Union of Soviet Socialist Republics and Yugoslavia,

Sept.14, 1937, 181 LNTS 135.

¹²⁹ Refer to § 13.2.2 (National Waters). For example, L.F.E. Goldie, Maritime War Zones & Exclusion Zones, 64

U.S. NAVAL WAR COLLEGE INTERNATIONAL LAW STUDIES 156, 189-90 (1991) (“At this point it may be noted in

passing that ‘Operation Market Time,’ which was enforced by the United States Navy during the Vietnamese War

was legally valid since it was a law-enforcement operation limited to a distance of twelve miles from the low water

mark of South Vietnam (it did not extend north beyond the DMZ) and so within the domestic competence of South

Vietnam, which legislated to empower the activity. Since that operation was conducted entirely within the territorial

sea and contiguous zone of South Vietnam, it does not come within the perspective of the present paper.”).

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over that airspace.¹³⁰ The right of a belligerent State to establish a zone outside its territory may

rely on the belligerent State’s:

(1) right to interdict contraband; (2) right to control the

immediate area of operations; or (3) right of blockade.¹³¹

Exclusion zones may also be established in accordance with an appropriate resolution

adopted by the U.N. Security Council.

13.9.2 Use of Zones to Warn Vessels or Aircraft - War, Operational, Warning, and

Safety Zones. A zone may be issued to advise vessels or aircraft to remain clear of an area of

naval operations. Such a zone may also provide procedures to reduce the risk of neutral vessels

being mistakenly attacked.¹³²

Such zones have been used: (1) to identify a particularly dangerous operational area;¹³³

(2) to assist in the defense of a particular area;¹³⁴ or (3) to assist in the defense of particular naval

forces (i.e., a defensive bubble).¹³⁵

¹³⁰ Refer to § 14.2.1.1 (National Airspace).

¹³¹ Refer to 15.12 (Neutral Commerce and Carriage of Contraband); § 13.8 (Belligerent Control of the Immediate

Area of Naval Operations); § 13.10 (Blockade).

¹³² For example, HYDROLANT 597/03 (54,56) EASTERN MEDITERRANEAN SEA (202135Z MAR 2003),

reprinted in 2007 NWP 1-14M, Appendix A (“2. ALL VESSELS SHOULD MAINTAIN A SAFE DISTANCE

FROM U.S. FORCES SO THAT INTENTIONS ARE CLEAR AND UNDERSTOOD BY U.S. FORCES.

VESSELS THAT ENTER THE MARITIME SAFETY ZONE WHICH ARE APPROACHING U.S. FORCES, OR

VESSELS WHOSE INTENTIONS ARE UNCLEAR ARE SUBJECT TO BOARDING AND VISIT BY U.S.

FORCES. ALL VESSELS APPROACHING U.S. FORCES ARE REQUESTED TO MAINTAIN RADIO

CONTACT WITH U.S. FORCES ON BRIDGE-TO-BRIDGE CHANNEL 16. 3. U.S. FORCES WILL EXERCISE

APPROPRIATE MEASURES IN SELF-DEFENSE IF WARRANTED BY THE CIRCUMSTANCES. VESSELS

APPROACHING U.S. FORCES WILL HELP MAKE THEIR INTENTIONS CLEAR AND AVOID

UNNECESSARY INITIATION OF SUCH DEFENSIVE MEASURES BY MAKING PRIOR CONTACT AS

DESCRIBED ABOVE.”).

¹³³ For example, HYDROLANT 597/03 (54,56) EASTERN MEDITERRANEAN SEA (202135Z MAR 2003),

reprinted in 2007 NWP 1-14M, Appendix A (“U.S. FORCES IN THE EASTERN MEDITERRANEAN HAVE

ESTABLISHED A MARITIME SAFETY ZONE AND ARE CONDUCTING COMBAT OPERATIONS IN

INTERNATIONAL WATERS THAT POSE A HAZARD TO NAVIGATION. ALL VESSELS ARE ADVISED

TO EXERCISE EXTREME CAUTION AND TO REMAIN CLEAR OF THE FOLLOWING DESIGNATED

OPERATION AREA BOUND BY 32-28.0N 033-22.0E, 31-40.0N 033-22.0E, 31-55.0N 032-20.0E, 32-46.8N 032-

20.0E.”).

¹³⁴ For example, Woodrow Wilson, Executive Order Establishing Defensive Sea Areas, No. 2584, Apr. 5, 1917,

reprinted in 12 AJIL SUPPLEMENT: OFFICIAL DOCUMENTS 13, 16 (1918) (“I, WOODROW WILSON, President of the

United States of America, do order that defensive sea areas are hereby established, to be maintained until further

notification, at the places and within the limits prescribed as follows, … The responsibility of the United States of

America for any damage inflicted by force of arms with the object of detaining any person or vessel proceeding in

contravention to Regulations duly promulgated in accordance with this Executive order shall cease from this date.”).

¹³⁵ For example, A.D. Parsons, Letter Dated 24 April 1982 from the Permanent Representative of the United

Kingdom of Great Britain and Northern Ireland to the United Nations Addressed to the President of the Security

Council, U.N. Doc. S/14997 (“Further to Mr. Whyte’s letter dated 9 April 1982 (S/14963), I have the honour, on

instructions from my Government, to inform you that the following communication was conveyed to the

Government of Argentina on 23 April 1982: In announcing the establishment of a maritime exclusion zone around

the Falkland Islands, Her Majesty’s Government made it clear that this measure was without prejudice to the right of

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The establishment of such a zone does not relieve the proclaiming belligerent State of its

obligation under the law of war to refrain from attacking vessels and aircraft that do not

constitute military objectives. Thus, a vessel or aircraft that is otherwise protected does not

forfeit its protection from being made the object of attack simply by entering a zone of the ocean

on the high seas established by a belligerent State.¹³⁶

In some cases, however, the fact that a vessel or aircraft enters a zone without

authorization may be probative in assessing whether it is entitled to protection (e.g., whether it is

an enemy military vessel or aircraft, or whether it has acquired the character of enemy military

vessels or aircraft).¹³⁷ For example, the notification of the zone in advance may mean that most

neutral or protected vessels and aircraft have departed the area. Similarly, the entry into the zone

of an unidentified vessel without authorization may be probative of whether the vessel

constitutes a military objective.

13.9.3 Use of Zones to Counter Enemy Logistics. Zones may be used to assist in the

implementation of the belligerent’s strategy to counter the adversary’s logistics.¹³⁸ For example,

zones may be established to facilitate the interdiction of contraband.¹³⁹ As a case in point, a

zone may be established to warn neutral vessels and aircraft that they will be subject to visit and

search if they attempt to enter the zone without authorization.

the United Kingdom to take whatever additional measures may be needed in the exercise of its right of self-defence

under Article 51 of the United Nations Charter. In this connection, Her Majesty’s Government now wishes to make

clear that any approach on the part of Argentine warships, including submarines, naval auxiliaries, or military

aircraft which could amount to a threat to interfere with the mission of the British forces in the South Atlantic, will

encounter the appropriate response. All Argentine aircraft including civil aircraft engaging in surveillance of these

British forces will be regarded as hostile and are liable to be dealt with accordingly.”).

¹³⁶ John H. McNeil, Neutral Rights and Maritime Sanctions: The Effects of Two Gulf Wars, 31 VIRGINIA JOURNAL

OF INTERNATIONAL LAW 631, 635-36 (1991) (“Iraq replied to these Iranian declarations by proclaiming a series of

escalating exclusion zones, beginning with a ‘prohibited war zone;’ Iraq declared that it would ‘attack all vessels’

appearing within these zones, and stated that ‘all tankers, regardless of nationality, docking at Kharg Island are

targets for the Iraqi Air Force.” As noted earlier, Iraq launched the Tanker War in 1984 in an apparent bid to

internationalize the war. During the first months of this new offensive, some seventy ships were hit, many of which

were neutral-flag tankers bound to or from the massive Iranian oil terminal at Kharg Island. But international law

has never legitimized attacks upon neutral merchant vessels simply because they ventured into a specified area of

the high seas.”).

¹³⁷ Refer to § 15.14.2.1 (Acquiring the Character of an Enemy Warship or Military Aircraft).

¹³⁸ For example, L.F.E. Goldie, Maritime War Zones & Exclusion Zones, 64 U.S. NAVAL WAR COLLEGE

INTERNATIONAL LAW STUDIES 156, 185-86 (1991) (“(a) The Exclusion Zone of the Skaggerak The Skaggerak is an

arm of the North Sea on its eastern side and lies between Denmark and Norway. It is some 150 nautical miles in

length and 85 miles in width. … The argument vindicating the British proclamation of the Skaggerak as a maritime

exclusion zone under emerging customary international law may be accepted, since the strategy for enforcing the

exclusion of the adversary from the zone was an apparently successful one. It was a persisting logistical strategy

enforced by both aircraft and submarines providing an adequate ratio of force to space. This proposition can be

analyzed out into the following elements. (i) The zone was reasonable in area, and despite German surface naval

power, the logistical strategy was persistently maintained and was made effective through submarine and aerial

warfare; (ii) The object, while not primarily one of self-defense, was for the related purposes of: … (b) encumbering

Germany’s reinforcements and supplies destined for its oppressive occupation of Norway—a victim of Nazi

aggression; (c) the target shipping had military objectives and purposes and could not be viewed as carrying supplies

which had the object of benefitting the civilian population of Norway;”).

¹³⁹ Refer to § 15.12 (Neutral Commerce and Carriage of Contraband).

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Zones may not be employed for the purpose of starving the civilian population.¹⁴⁰ Such

zones must not impose an unreasonable burden on neutral commerce in free goods.¹⁴¹

13.9.4 Use of Zones to Prevent Movement - Exclusion Zones. Belligerents may

establish exclusion zones that prohibit the entry of vessels or aircraft without authorization from

that belligerent.¹⁴² Such zones may suspend the right of innocent passage through non-neutral

waters.¹⁴³

The extent, location, and duration of the exclusion zone and the measures imposed should

not exceed what is required by military necessity.¹⁴⁴

Belligerents establishing such zones must provide safe passage through the zone for

neutral vessels and aircraft where the geographical extent of the zone significantly impedes free

¹⁴⁰ Refer to § 5.20 (Starvation).

¹⁴¹ See 2007 NWP 1-14M ¶7.9 (“To the extent that such zones serve to warn neutral vessels and aircraft away from

belligerent activities and thereby reduce their exposure to collateral damage and incidental injury (see paragraph

8.3.1), and to the extent that they do not unreasonably interfere with legitimate neutral commerce, they are

undoubtedly lawful.”).

¹⁴² For example, 2004 UK MANUAL ¶12.58 footnote 76 (“During the Falklands conflict 1982, a total exclusion zone

of 200 nautical miles was established around the Islands. It applied, inter alia, to any aircraft, military or civil,

operating in support of the illegal occupation by the Argentine forces, and any aircraft (military or civil) found

within the zone without authority from the Ministry of Defence would be regarded as operating in support of the

illegal occupation and thus hostile and liable to be attacked by the British forces.”).

¹⁴³ For example, HYDROPAC 795/2004 (62) PERSIAN GULF (030850Z MAY 2004), reprinted in 2007 NWP 1-

14M, Appendix C (“8. ADDITIONALLY, EFFECTIVE IMMEDIATELY, EXCLUSION ZONES ARE

ESTABLISHED AND THE RIGHT OF INNOCENT PASSAGE IS TEMPORARILY SUSPENDED IN

ACCORDANCE WITH INTERNATIONAL LAW AROUND THE KAAOT AND ABOT OIL TERMINALS

WITHIN IRAQI TERRITORIAL WATERS. THE EXCLUSION ZONES EXTEND 2000 METERS FROM THE

OUTER EDGES OF THE TERMINAL STRUCTURES IN ALL DIRECTIONS. 9. ONLY TANKERS AND

SUPPORT VESSELS AUTHORIZED BY TERMINAL OPERATORS OR COALITION MARITIME SECURITY

FORCES ARE ALLOWED TO ENTER THE EXCLUSION ZONES. VESSELS ATTEMPTING TO ENTER THE

ZONES WITHOUT AUTHORIZATION MAY BE SUBJECT TO DEFENSIVE MEASURES, INCLUDING

WHEN NECESSARY, THE USE OF DEADLY FORCE. ALL REASONABLE EFFORTS WILL BE TAKEN TO

WARN VESSELS AWAY BEFORE EMPLOYING DEADLY FORCE. HOWEVER, DEADLY FORCE WILL

BE EMPLOYED WHEN NECESSARY TO PROTECT COALITION MARITIME SECURITY FORCES,

LEGITIMATE SHIPPING PRESENT IN THE EXCLUSION ZONES AND THE OIL TERMINALS.”).

¹⁴⁴ For example, Wolff Heintschel von Heinegg, The Law of Armed Conflict at Sea, in DIETER FLECK, THE

HANDBOOK OF HUMANITARIAN LAW IN ARMED CONFLICTS 467 (¶1049) (“On 28 April 1982 Great Britain

proclaimed a ‘Total Exclusion Zone’ (TEZ) in the South Atlantic. Beside deterring the Argentine naval forces from

leaving their ports, its main purpose was to facilitate the early identification of military objectives and to prevent

vessels flying neutral flags from conveying information to Argentina. … On one hand, the British TEZ covered an

area of 200 nautical miles measured from the centre of the main island. On the other hand, the TEZ was situated far

from any main shipping lanes. Moreover, its duration was comparatively short. It did not serve economic warfare

purposes but was aimed at facilitating military operations, including identification. Vessels and aircraft flying flags

of states not parties to the conflict suffered no damage whatsoever. For these reasons, only the former USSR

officially protested against the British TEZ.”).

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and safe access to the ports and coasts of a neutral State and, unless military requirements do not

permit, in other cases where normal navigation routes are affected.¹⁴⁵

13.9.5 Procedures for Declaring a Zone. As a matter of practice, maritime and/or aerial

warnings (e.g., HYDROLANT, HYDROPAC, Notice to Airmen (NOTAM)) would ordinarily be

promulgated as part of the establishment of a maritime or airspace zone.

13.10 BLOCKADE

A blockade is an operation by a belligerent State to prevent vessels and/or aircraft of all

States, enemy as well as neutral, from entering or exiting specified ports, airfields, or coastal

areas belonging to, occupied by, or under the control of an enemy belligerent State.¹⁴⁶

13.10.1 Purpose of Blockade and Belligerent Rights Associated With Blockade. The

purpose of a blockade is to deprive the adversary of supplies needed to conduct hostilities.¹⁴⁷

A blockade enables the blockading State to control traffic in the blockaded area. A

blockade also enables the blockading State to take measures on the high seas to deny supplies to

a blockaded area.¹⁴⁸ For example, a blockading State has the right to visit and search vessels on

the high seas to enforce its blockade.¹⁴⁹

13.10.2 Criteria for Blockades. In order to be binding, a blockade must meet certain

criteria.

13.10.2.1 Authority for the Establishment of a Blockade. A blockade must be

established by proper legal authority. The establishment of a blockade has been accomplished

¹⁴⁵ 2007 NWP 1-14M ¶7.9 (“Belligerents creating such zones must provide safe passage through the zone for neutral

vessels and aircraft where the geographical extent of the zone significantly impedes free and safe access to the ports

and coasts of a neutral state and, unless military requirements do not permit, in other cases where normal navigation

routes are affected.”).

¹⁴⁶ 2007 NWP 1-14M ¶7.7.1 (“Blockade is a belligerent operation to prevent vessels and/or aircraft of all nations,

enemy as well as neutral, from entering or exiting specified ports, airfields, or coastal areas belonging to, occupied

by, or under the control of an enemy nation.”); 1997 NWP 9 ¶7.7.1 (same); 1989 NWP 9 ¶7.7.1 (same); 1955 NWIP

10-2 ¶632a (“A blockade is a belligerent operation intended to prevent vessels of all States from entering or leaving

specified coastal areas which are under the sovereignty, under the occupation, or under the control of an enemy.”).

¹⁴⁷ ICRC AP COMMENTARY 654 (¶2095) (“It should be emphasized that the object of a blockade is to deprive the

adversary of supplies needed to conduct hostilities, and not to starve civilians.”).

¹⁴⁸ John Reese Stevenson, Department of State, Legal Adviser, Letter dated June 6, 1972, reprinted in Steven C.

Nelson, Contemporary Practice of the United States Relating to International Law, 66 AJIL 836, 837 (1972) (“To

have declared a blockade could have implied, under traditional international law, a whole range of actions which

would have extended the area of hostilities and risked grave dangers of widening the conflict. The traditional law of

blockade requires a formal declaration of the establishment of the blockade and notification of it to all states. A

blockade must be ‘effective’ in preventing all ingress or egress—including commercial trade and activities—from or

to the enemy's coast. The blockading state would have the right to stop vessels of any nation anywhere on the high

seas, to inspect and search such vessels, to seize them if they are bound to or from the blockaded ports, and

eventually to condemn them and their cargos in a prize court. Ships attempting to violate the blockade could be

taken under fire should they fail to stop on order.”).

¹⁴⁹ Refer to § 15.13.1 (Purposes of Visit and Search).

886

by a declaration of the belligerent State, or by the commander of the blockading force acting on

behalf of the belligerent State.¹⁵⁰

The U.N. Security Council is also expressly given the authority by the Charter of the

United Nations to authorize blockades.¹⁵¹ A blockade of the ports or coasts of a State is

generally regarded as a measure involving force against that State for the purposes of the Charter

of the United Nations.¹⁵²

13.10.2.2 Notification of the Blockade. It is customary for the belligerent State

establishing the blockade to notify all affected States of its imposition.¹⁵³ The commander of the

blockading forces will usually also notify local authorities in the blockaded area.¹⁵⁴

Notification should include, as a minimum, the date the blockade is to begin, its

geographic limits, and the grace period granted neutral vessels and aircraft to leave the area to be

blockaded.¹⁵⁵

¹⁵⁰ Consider DECLARATION OF LONDON art. 9 (1909) (“A declaration of a blockade is made either by the blockading

Power or by the naval authorities acting in its name.”).

¹⁵¹ Refer to § 1.11.4.2 (Use of Force Authorized by the U.N. Security Council Acting Under Chapter VII of the

Charter of the United Nations).

¹⁵² See, e.g., Legal and Practical Consequences of a Blockade of Cuba, Oct. 19, 1962, 1 SUPPLEMENTAL OPINIONS

OF THE OFFICE OF LEGAL COUNSEL 486, 490 (2013) (“The legality today of a blockade unilaterally imposed by one

state upon another depends upon its compatibility with the language and principles of the Charter. Ordinarily it, like

other measures involving force, is reserved to the United Nations or to regional organizations such as the OAS. If

imposed unilaterally without prior approval it must be considered a reasonable measure under the circumstances,

proportional to the threat posed, and limited to a legitimate purpose. It does not become more or less lawful on the

basis of declaration of war or a failure to declare war.”); Definition of Aggression, arts. 1, 3, Annex to U.N.

GENERAL ASSEMBLY RESOLUTION 3314 (XXIX), Definition of Aggression, U.N. Doc. A/RES/3314 (XXIX) (Dec.

14, 1974) (“Aggression is the use of armed force by a State against the sovereignty, territorial integrity or political

independence of another State, or in any other manner inconsistent with the Charter of the United Nations, as set out

in this Definition. … Any of the following acts, regardless of a declaration of war, shall, subject to and in

accordance with the provisions of article 2, qualify as an act of aggression: ... (c) The blockade of the ports or coasts

of a State by the armed forces of another State.”).

¹⁵³ 2007 NWP 1-14M ¶7.7.2.2 (“It is customary for the belligerent nation establishing the blockade to notify all

affected nations of its imposition.”); 1955 NWIP 10-2 ¶632b (“It is customary for the blockade to be notified in a

suitable manner to the governments of all States.”). Consider 1909 DECLARATION OF LONDON art. 11 (“A

declaration of blockade is notified- (1) to neutral Powers, by the blockading Power, by means of a communication

addressed to the Governments direct, or to their representatives accredited to it.”).

¹⁵⁴ 2007 NWP 1-14M ¶7.7.2.2 (“The commander of the blockading forces will usually also notify local authorities in

the blockaded area.”); 1955 NWIP 10-2 ¶632b (“The commander of the blockading force usually makes notification

to local authorities in the blockaded area.”). Consider 1909 DECLARATION OF LONDON art. 11 (“A declaration of

blockade is notified- … (2) to the local authorities, by the officer commanding the blockading force. The local

authorities will, in turn, inform the foreign consular officers at the port or on the coastline under blockade as soon as

possible.”).

¹⁵⁵ 2007 NWP 1-14M ¶7.7.2.1 (“The declaration should include, as a minimum, the date the blockade is to begin, its

geographic limits, and the grace period granted neutral vessels and aircraft to leave the area to be blockaded.”); 1955

NWIP 10-2 ¶632b (“The declaration should include the date the blockade begins, the geographical limits of the

blockade, and the period granted neutral vessels and aircraft to leave the blockaded area.”). Consider 1909

DECLARATION OF LONDON art. 9 (“A declaration of blockade is made either by the blockading Power or by the naval

887

The form of the notification is not material so long as it is effective, and a variety of

methods may be used.¹⁵⁶

The notification of the blockade may establish a presumption of knowledge of the

blockade that is required in the offense of breach or attempted breach of a blockade.¹⁵⁷

13.10.2.3 Effectiveness of the Blockade. In order to be binding, a blockade must

be effective.¹⁵⁸ This requirement of effectiveness is intended to prevent “paper” blockades.¹⁵⁹

The requirement of effectiveness means that the blockade must be maintained by forces

that are sufficient to render ingress or egress of the blockaded area dangerous.¹⁶⁰ The

authorities acting in its name. It specifies- (1) The date when the blockade begins; (2) The geographical limits of

the coastline under blockade; (3) The period within which neutral vessels may come out.”).

¹⁵⁶ For example, The Public Commission to Examine the Maritime Incident of 31 May 2010, et. al (The Turkel

Commission), Report: Part one, 162-63 (¶58) (Jan. 2010) (“In the case at hand, the State of Israel took the following

steps in order to give notice of the naval blockade: from the testimony of the Military Advocate-General, Major-

General Avichai Mendelblit, it can be seen that the Military Advocate-General’s Office asked the Ministry of

Transport to transmit information regarding the imposition of the naval blockade by all methods at its disposal, in

order to ensure that the notice would reach all vessels in the Mediterranean Sea. This was also done. The notice

was also published on the Internet sites of the IDF, the Shipping Authority, the Military Advocate-General, and the

Ministry of Transport, and, as noted above, via several international channels. The announcement was also

transmitted twice a day via the emergency channel for maritime communication to all ships within a distance of up

to 300 kilometers from the Israeli coast. In addition, notices were also sent to the flag States and the States that

Israel knew intended to send ships to the area. These steps clearly satisfy the requirement of ‘notice.’”).

¹⁵⁷ Refer to § 13.10.4.2 (Knowledge of the Existence of Blockade).

¹⁵⁸ Consider 1909 DECLARATION OF LONDON art. 2 (“In accordance with the Declaration of Paris of 1856, a

blockade, in order to be binding must be effective - that is to say, it must be maintained by a force sufficient really

to prevent access to the enemy coastline.”); Declaration respecting maritime law signed by the Plenipotentiaries of

Great Britain, Austria, France, Prussia, Russia, Sardinia, and Turkey, assembled in Congress at Paris, Apr. 16, 1856,

reprinted in 1 AJIL SUPPLEMENT: OFFICIAL DOCUMENTS 89 (1907) (“4. Blockades, in order to be binding, must be

effective, that is to say, maintained by a force sufficient really to prevent access to the coast of the enemy.”).

¹⁵⁹ The Peterhoff, 72 U.S. 28, 50 (1867) (“It must be premised that no paper or constructive blockade is allowed by

international law. When such blockades have been attempted by other nations, the United States have ever protested

against them and denied their validity. Their illegality is now confessed on all hands. It was solemnly proclaimed

in the Declaration of Paris of 1856, to which most of the civilized nations of the world have since adhered; and this

principle is nowhere more fully recognized than in our own country, though not a party to that declaration.”); The

Olinde Rodrigues, 174 U.S. 510, 513-14 (1899) (“The fourth maxim of the Declaration of Paris (April 16, 1856)

was: ‘Blockades, in order to be binding, must be effective, that is to say, maintained by a force sufficient really to

prevent access to the coast of the enemy.’ Manifestly this broad definition was not intended to be literally applied.

The object was to correct the abuse, in the early part of the century, of paper blockades, where extensive coasts were

put under blockade by proclamation, without the presence of any force, or an inadequate force; and the question of

what might be sufficient force was necessarily left to be determined according to the particular circumstances.”).

¹⁶⁰ See 2007 NWP 1-14M ¶7.7.2.3 (“To be valid, a blockade must be effective—that is, it must be maintained by a

surface, air, or subsurface force or other legitimate methods and means of warfare that is sufficient to render ingress

or egress of the blockaded area dangerous.”); 1955 NWIP 10-2 ¶632d (“A blockade, in order to be binding, must be

effective. This means that a blockade must be maintained by a force sufficient to render ingress and egress to or

from the blockaded area dangerous.”); The Olinde Rodrigues, 174 U.S. 510, 515 (1899) (“Such is the settled

doctrine of the English and American courts and publicists, and it is embodied in the second of the instructions

issued by the Secretary of the Navy, June 20, 1898, General Order No. 492: ‘A blockade to be effective and binding

must be maintained by a force sufficient to render ingress to or egress from the port dangerous.’”);

888

requirement of effectiveness does not preclude temporary absence of the blockading force, if

such absence is due to stress of weather or to some other reason connected with the blockade

(e.g., pursuit of a blockade runner).¹⁶¹

The forces that are necessary to make a blockade effective depend on the specific military

circumstances.¹⁶² The blockade may be maintained by forces that are some distance from the

shore.¹⁶³

13.10.2.4 Impartial Application of the Blockade. A blockade must be applied

impartially to the vessels and aircraft of all States.¹⁶⁴ The requirement that a belligerent must

apply a blockade impartially to the vessels and aircraft of all States is intended to prevent

measures of discrimination by the blockading belligerent in favor of or against the vessels and

aircraft of particular States, including its own or allied vessels and aircraft.¹⁶⁵

13.10.2.5 Limitations on the Scope of the Blockade. A blockade must not bar

access to, or departure from, neutral ports and coasts.¹⁶⁶

A blockade may not be used for the purpose of starving the civilian population, and the

expected incidental harm to the civilian population may not be excessive in relation to the

expected military advantage to be gained from employing the blockade.¹⁶⁷

¹⁶¹ 2007 NWP 1-14M ¶7.7.2.3 (“The requirement of effectiveness does not preclude temporary absence of the

blockading force, if such absence is due to stress of weather or to some other reason connected with the blockade

(e.g., pursuit of a blockade runner).”). Consider 1909 DECLARATION OF LONDON art. 4 (“A blockade is not regarded

as raised if the blockading force is temporarily withdrawn on account of stress of weather.”).

¹⁶² See The Olinde Rodrigues, 174 U.S. 510, 516-18 (1899) (“As we hold that an effective blockade is a blockade so

effective as to make it dangerous in fact for vessels to attempt to enter the blockaded port, it follows that the

question of effectiveness is not controlled by the number of the blockading force. In other words, the position

cannot be maintained that one modern cruiser though sufficient in fact is not sufficient as matter of law. … The

question of effectiveness must necessarily depend on the circumstances. We agree that the fact of a single capture is

not decisive of the effectiveness of a blockade, but the case made on this record does not rest on that ground. We

are of opinion that if a single modern cruiser blockading a port renders it in fact dangerous for other craft to enter the

port, that is sufficient, since thereby the blockade is made practically effective.”).

¹⁶³ 2013 GERMAN MANUAL ¶1062 (“A blockade, in order to be binding, must be effective (25 Principle 4). It must

be maintained by armed forces sufficient to prevent access to the blockaded coast. Long distance blockades are

also permissible, i.e. the blockade and control of an enemy coast by armed forces at a greater distance from the

blockaded coast as a result of military requirements.”); 2004 UK MANUAL ¶13.68 (“The force maintaining the

blockade may be stationed at a distance determined by military requirements.”).

¹⁶⁴ 1955 NWIP 10-2 ¶632f (“A blockade must be applied equally (impartially) to the vessels and aircraft of all

states.”). Consider 1909 DECLARATION OF LONDON art. 5 (“A blockade must be applied impartially to the ships of

all nations.”).

¹⁶⁵ 1955 NWIP 10-2 ¶632f note 35 (“The requirement that a belligerent must apply a blockade impartially to the

vessels and aircraft of all states is intended to prevent measures of discrimination by the blockading belligerent in

favor of or against the vessels and aircraft of particular states, including its own or allied vessels and aircraft.”).

¹⁶⁶ 1955 NWIP 10-2 ¶632e (“A blockade must not bar access or departure from neutral ports or coasts.”). Consider

1909 DECLARATION OF LONDON art. 18 (“The blockading forces must not bar access to neutral ports or coasts.”).

¹⁶⁷ Refer to § 5.20 (Starvation).

889

13.10.3 Special Entry and Exit Authorization. In certain cases, vessels or aircraft may

enter or exit a blockaded area.

13.10.3.1 Neutral Warships and Military Aircraft. Although neutral warships and

military aircraft enjoy no positive right of access to blockaded areas, the belligerent State

imposing the blockade may authorize their entry and exit. Such special authorization may be

made subject to such conditions as the blockading force considers necessary and expedient.¹⁶⁸

13.10.3.2 Neutral Vessels and Aircraft in Evident Distress. Neutral vessels and

aircraft in evident distress should be authorized entry into a blockaded area, and subsequently

authorized to depart, under conditions prescribed by the officer in command of the blockading

force or responsible for maintenance of the blockading instrumentality (e.g., mines).¹⁶⁹

13.10.3.3 Passage of Relief Consignments Under the GC. Similarly, neutral

vessels and aircraft engaged in the carriage of qualifying relief supplies for the civilian

population and the sick and wounded should be authorized to pass through the blockade cordon,

subject to the right of the blockading force to prescribe the technical arrangements, including

search, under which passage is permitted.¹⁷⁰

13.10.4 Breach and Attempted Breach of Blockade. Breach or attempted breach of a

blockade subjects a neutral vessel or aircraft to capture.¹⁷¹

13.10.4.1 Acts of Breach or Attempted Breach of Blockade. Breach of blockade is

the passage of a vessel or aircraft through a blockade without special entry or exit authorization

from the blockading belligerent.¹⁷²

¹⁶⁸ See 2007 NWP 1-14M ¶7.7.3 (“Although neutral warships and military aircraft enjoy no positive right of access

to blockaded areas, the belligerent imposing the blockade may authorize their entry and exit. Such special

authorization may be made subject to such conditions as the blockading force considers to be necessary and

expedient.”); 1955 NWIP 10-2 ¶632h(1) (“Neutral warships and neutral military aircraft have no positive right of

entry to a blockaded area. However, they may be allowed to enter or leave a blockaded area as a matter of courtesy.

Permission to visit a blockaded area is subject to any conditions, such as the length of stay, that the senior officer of

the blockading force may deem necessary and expedient.”). Consider 1909 DECLARATION OF LONDON art. 6 (“The

commander of a blockading force may give permission to a warship to enter, and subsequently leave, a blockaded

port.”).

¹⁶⁹ See 2007 NWP 1-14M ¶7.7.3 (“Neutral vessels and aircraft in evident distress should be authorized entry into a

blockaded area, and subsequently authorized to depart, under conditions prescribed by the officer in command of the

blockading force or responsible for maintenance of the blockading instrumentality (e.g., mines).”); 1955 NWIP 10-2

¶632h(2) (“Neutral vessels and aircraft in urgent distress may be permitted to enter a blockaded area, and

subsequently to leave it, under conditions prescribed by the commander of the blockading force.”). Consider 1909

DECLARATION OF LONDON art. 7 (“In circumstances of distress, acknowledged by an officer of the blockading force,

a neutral vessel may enter a place under blockade and subsequently leave it, provided that she has neither discharged

nor shipped any cargo there.”).

¹⁷⁰ 2007 NWP 1-14M ¶7.7.3 (“Similarly, neutral vessels and aircraft engaged in the carriage of qualifying relief

supplies for the civilian population and the sick and wounded should be authorized to pass through the blockade

cordon, subject to the right of the blockading force to prescribe the technical arrangements, including search, under

which passage is permitted.”). Refer to § 5.19.3 (Passage of Relief Consignments).

¹⁷¹ Refer to § 15.15.1 (Grounds for the Capture of Neutral Vessels and Aircraft).

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Attempted breach of a blockade occurs from the time a vessel or aircraft leaves a port or

airfield with the intention of evading the blockade and, for vessels exiting the blockaded area,

continues until the voyage is completed.¹⁷³ A temporary anchorage in waters occupied by the

blockading vessels does not justify capture, in the absence of other grounds.¹⁷⁴

A presumption arises that certain merchant vessels or aircraft are attempting to breach a

blockade where those vessels or aircraft are bound for a neutral port or airfield serving as a point

of transit to the blockaded area.¹⁷⁵

13.10.4.2 Knowledge of the Existence of Blockade. Knowledge of the existence

of the blockade is essential to the offenses of breach of blockade and attempted breach of

blockade; presumed knowledge is sufficient.¹⁷⁶

Knowledge may be presumed once a blockade has been declared and appropriate

notification provided to affected governments.¹⁷⁷ For example, a vessel in a blockaded port is

presumed to have notice of the blockade as soon as it commences.¹⁷⁸

¹⁷² 2007 NWP 1-14M ¶7.7.4 (“Breach of blockade is the passage of a vessel or aircraft through a blockade without

special entry or exit authorization from the blockading belligerent.”); 1997 NWP 9 ¶7.7.4 (same); 1989 NWP 9

¶7.7.4 (same); 1955 NWIP 10-2 ¶632g (“Breach of blockade is the passage of a vessel or aircraft through the

blockade.”).

¹⁷³ 2007 NWP 1-14M ¶7.7.4 (“Attempted breach of blockade occurs from the time a vessel or aircraft leaves a port

or airfield with the intention of evading the blockade, and for vessels exiting the blockaded area, continues until the

voyage is completed.”); 1997 NWP 9 ¶7.7.4 (same); 1989 NWP 9 ¶7.7.4 (substantially similar); 1955 NWIP 10-2

¶632g(2) (“Attempted breach of blockade occurs from the time a vessel or aircraft leaves a port or air take-off point

with the intent of evading the blockade.”).

¹⁷⁴ The Teresita, 72 U.S. 180, 182 (1867) (“We are of opinion that, under such circumstances, temporary anchorage

in waters occupied by the blockading vessels, does not justify capture, in the absence of other grounds.”).

¹⁷⁵ 2007 NWP 1-14M ¶7.7.4 (“There is a presumption of attempted breach of blockade where vessels or aircraft are

bound for a neutral port or airfield serving as a point of transit to the blockaded area.”); 1955 NWIP 10-2 ¶632g(1)

(“There is a presumption of attempted breach of blockade where vessels and aircraft are bound to a neutral port or

airfield serving as a point of transit to the blockaded area.”); The Peterhoff, 72 U.S. 28, 55 (1867) (“It is an

undoubted general principle, recognized by this court in the case of The Bermuda, and in several other cases, that an

ulterior destination to a blockaded port will infect the primary voyage to a neutral port with liability for intended

violation of blockade.”). Compare § 15.12.2 (Requirement of Enemy Destination).

¹⁷⁶ 2007 NWP 1-14M ¶7.7.4 (“Knowledge of the existence of the blockade is essential to the offenses of breach of

blockade and attempted breach of blockade.”); 1997 NWP 9 ¶7.7.4 (same); 1989 NWP 9 ¶7.7.4 (same); 1955 NWIP

10-2 ¶632g (“Knowledge of the existence of a blockade is essential to the offenses of breach of blockade and

attempted breach of blockade; presumed knowledge is sufficient.”). Consider 1909 DECLARATION OF LONDON art.

14 (“The liability of a neutral vessel to capture for breach of blockade is contingent on her knowledge, actual or

presumptive, of the blockade.”).

¹⁷⁷ 2007 NWP 1-14M ¶7.7.4 (“Knowledge may be presumed once a blockade has been declared and appropriate

notification provided to affected governments.”); 1997 NWP 9 ¶7.7.4 (same); 1989 NWP 9 ¶7.7.4 (same). Consider

1909 DECLARATION OF LONDON art. 15 (“Failing proof to the contrary, knowledge of the blockade is presumed if

the vessel left a neutral port subsequently to the notification of the blockade to the Power to which such port

belongs, provided that such notification was made in sufficient time.”).

¹⁷⁸ The Prize Cases, 67 U.S. 635, 677 (1863) (“A vessel being in a blockaded port is presumed to have notice of the

blockade as soon as it commences. This is a settled rule in the law of nations.”).

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A vessel sailing ignorantly (i.e., with neither presumptive nor actual knowledge) to a

blockaded port is not liable to capture, although it may be turned away from the blockaded

area.¹⁷⁹

13.11 NAVAL MINES

Naval mines are lawful weapons, i.e., they are not illegal per se.¹⁸⁰ However, specific

rules apply to their use. These rules have developed largely to mitigate the risk these mines pose

to neutral vessels.¹⁸¹ Different rules apply to landmines.¹⁸²

13.11.1 Background on Naval Mines. Naval mines have been used for area denial,

coastal and harbor defense, anti-surface and anti-submarine warfare, and blockade.

Naval mines are sometimes classified as either armed or controlled mines, with

controlled mines having no destructive capability until affirmatively activated by an arming

order (thereby becoming armed mines).¹⁸³

¹⁷⁹ Yeaton v. Fry, 9 U.S. 335, 342-43 (1809) (Marshall, C.J.) (“Hispaniola is excepted absolutely from the policy;

but other ports are within the terms of the voyage insured, if they be not blockaded. It is their character, as

blockaded ports, which excludes them from the insurance. Their being excepted by this character is thought to

justify the opinion, that it is the risk attending this character which produces the exception, and which is the risk

excepted. The risk of a blockaded port, as a blockaded port, is the risk incurred by breaking the blockade. This is

defined by public law. Sailing from Tobago for Curracoa, knowing Curracoa to be blockaded, would have incurred

this risk, but sailing for that port, without such knowledge, did not incur it.”).

¹⁸⁰ Refer to § 6.5 (Lawful Weapons).

¹⁸¹ For example, A. PEARCE HIGGINS, THE HAGUE PEACE CONFERENCES AND OTHER INTERNATIONAL CONFERENCES

CONCERNING THE LAWS AND USAGES OF WAR. TEXT OF CONVENTIONS WITH COMMENTARIES 328-29 (1909) (“The

Russo-Japanese War drew the attention of the world to the deadly results produced by floating mines. Though not

expressly mentioned in Count Benckendorff’s Circular, the laying of torpedoes, etc. (pose de torpilles, etc.) was

included among the subjects for consideration. Mines were employed in the Russo-Japanese War by both

belligerents, and hundreds either broke adrift from their moorings or, not be anchored at all, floated into the high

seas and caused serious loss of life to neutrals long after the conclusion of the war. In the course of the discussion of

the British proposal in Committee, the Chinese delegate made the following declaration which brings out strongly

the dangers to which neutral shipping is exposed by their employment: ‘At the same time, the Delegation [of China]

desires to bring to the knowledge of the delegates certain facts which it ventures to hope will suggest the

examination of this important proposition in a widely humanitarian sense. The Chinese Government is even to-day

obliged to furnish vessels engaged in coastal navigation with special apparatus to raise and destroy floating mines

which are found not only on the open sea but even in its territorial waters. In spite of the precautions which have

been taken a very considerable number of coasting vessels, fishing boats, junks and sampans have been lost with all

hands without the details of these disasters being known to the western world. It is calculated from five to six

hundred of our countrymen engaged in their peaceful occupations have there met a cruel death in consequence of

these dangerous engines of war.’”) (amendment in original).

¹⁸² Refer to § 6.12 (Landmines, Booby-Traps, and Other Devices).

¹⁸³ 2007 NWP 1-14M ¶9.2.1 (“For purposes of this publication, naval mines are classified as armed or controlled

mines. Armed mines are either emplaced with all safety devices withdrawn, or are armed following emplacement,

so as to detonate when preset parameters (if any) are satisfied. Controlled mines have no destructive capability until

affirmatively activated by some form of arming order (whereupon they become armed mines).”); 1989 NWP 9

¶9.2.1 (“For purposes of this publication, naval mines are classified as armed or controlled mines. Armed mines are

either emplaced with all safety devices withdrawn, or are armed following emplacement, so as to detonate when

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13.11.2 Peacetime Mining. Naval mines may not be emplaced in internal waters, the

territorial sea, or archipelagic waters of another State in peacetime without that State’s

consent.¹⁸⁴

13.11.2.1 A State’s Archipelagic Waters and Territorial Sea. A State’s right to

mine its archipelagic waters and territorial sea during peacetime is subject to the right of

innocent passage of foreign vessels.¹⁸⁵

If armed mines are emplaced in a State’s own archipelagic waters or territorial sea,

appropriate international notification of the existence and location of such mines is required.¹⁸⁶

Because the right of innocent passage may be suspended only temporarily,¹⁸⁷ armed mines must

be removed or rendered harmless as soon as the security threat that prompted their emplacement

has terminated.¹⁸⁸

Armed mines may not be emplaced in international straits or archipelagic sea lanes

during peacetime.¹⁸⁹

Emplacement of controlled mines in a State’s own archipelagic waters or territorial sea is

not subject to notification or removal requirements.¹⁹⁰

preset parameters (if any) are satisfied. Controlled mines have no destructive capability until affirmatively activated

by some form of controlled arming order (whereupon they become armed mines).”).

¹⁸⁴ 2007 NWP 1-14M ¶9.2.2 (“Naval mines may not be emplaced in internal waters, territorial seas, or archipelagic

waters of another nation in peacetime without that nation’s consent.”). See also Military and Paramilitary Activities

in and Against Nicaragua (Nicaragua v. United States), Merits, Judgment, 1986 I.C.J. 14, 111-12 (¶¶213-15) (“The

legal rules in the light of which these acts of mining should be judged depend upon where they took place. The

laying of mines within the ports of another State is governed by the law relating to internal waters, which are subject

to the sovereignty of the coastal State. The position is similar as regards mines placed in the territorial sea. It is

therefore the sovereignty of the coastal State which is affected in such cases. … It has already been made clear

above that in peacetime for one State to lay mines in the internal or territorial waters of another is an unlawful act;”).

¹⁸⁵ Refer to § 13.2.2.4 (Innocent Passage of Foreign Vessels Through Territorial Seas and Archipelagic Waters).

¹⁸⁶ Corfu Channel Case (United Kingdom v. Albania), Merits, Judgment, 1949 I.C.J. 4, 22 (“The obligations

incumbent upon the Albanian authorities consisted in notifying, for the benefit of shipping in general, the existence

of a minefield in Albanian territorial waters and in warning the approaching British warships of the imminent danger

to which the minefield exposed them. Such obligations are based, not on the Hague Convention of 1907, No. VIII,

which is applicable in time of war, but on certain general and well-recognized principles, namely: elementary

considerations of humanity, even more exacting in peace than in war; the principle of the freedom of maritime

communication; and every State’s obligation not to allow knowingly its territory to be used for acts contrary to the

rights of other States.”).

¹⁸⁷ Refer to § 13.2.2.4 (Innocent Passage of Foreign Vessels Through Territorial Seas and Archipelagic Waters).

¹⁸⁸ 2007 NWP 1-14M ¶9.2.2 (“Because the right of innocent passage can be suspended only temporarily, armed

mines must be removed or rendered harmless as soon as the security threat that prompted their emplacement has

terminated.”); 1997 NWP 9 ¶9.2.2 (same); 1989 NWP 9 ¶9.2.2 (same).

¹⁸⁹ 2007 NWP 1-14M ¶9.2.2 (“Armed mines may not be emplaced in international straits or archipelagic sea lanes

during peacetime.”); 1997 NWP 9 ¶9.2.2 (same).

¹⁹⁰ 2007 NWP 1-14M ¶9.2.2 (“Emplacement of controlled mines in a nation’s own archipelagic waters or territorial

sea is not subject to such notification or removal requirements.”); 1997 NWP 9 ¶9.2.2 (same); 1989 NWP 9 ¶9.2.2

(same).

893

13.11.2.2 International Waters. Controlled mines may be emplaced in

international waters (i.e., beyond the territorial sea of any State) if they do not unreasonably

interfere with other lawful uses of the oceans. What constitutes an “unreasonable interference”

may involve a number of factors, including:

• the rationale for their emplacement (e.g., the self-defense requirements of the emplacing

State);

• the extent of the area to be mined;

• the hazard (if any) to other lawful ocean uses; and

• the duration of their emplacement.¹⁹¹

Because controlled mines do not constitute a hazard to navigation, international notice of

their emplacement is not required.¹⁹²

Armed mines may not be emplaced in international waters prior to the outbreak of armed

conflict, except under the most demanding requirements of individual or collective self-defense.

Should armed mines be emplaced in international waters under such circumstances, prior

notification of their location must be provided. A State emplacing armed mines in international

waters during peacetime must maintain an on-scene presence in the area sufficient to ensure that

appropriate warning is provided to ships approaching the danger area. All armed mines must be

expeditiously removed or rendered harmless when the imminent danger that prompted their

emplacement has passed.¹⁹³

13.11.3 Naval Mining During Armed Conflict. Belligerent States may lawfully employ

naval mines subject to certain restrictions.

Neutral States that lay automatic contact mines off their coasts must observe the same

rules and take the same precautions as those that are imposed on belligerents.¹⁹⁴ In addition, a

neutral State must inform ship owners, by a notice issued in advance, where automatic contact

¹⁹¹ 2007 NWP 1-14M ¶9.2.2 (“The determination of what constitutes an ‘unreasonable interference’ involves a

balancing of a number of factors, including the rationale for their emplacement (i.e., the self-defense requirements of

the emplacing nation), the extent of the area to be mined, the hazard (if any) to other lawful ocean uses, and the

duration of their emplacement.”).

¹⁹² 2007 NWP 1-14M ¶9.2.2 (“Because controlled mines do not constitute a hazard to navigation, international

notice of their emplacement is not required.”); 1997 NWP 9 ¶9.2.2 (same); 1989 NWP 9 ¶9.2.2 (same).

¹⁹³ 2007 NWP 1-14M ¶9.2.2 (“Armed mines may not be emplaced in international waters prior to the outbreak of

armed conflict, except under the most demanding requirements of individual or collective self-defense. Should

armed mines be emplaced in international waters under such circumstances, prior notification of their location must

be provided. A nation emplacing armed mines in international waters during peacetime must maintain an on-scene

presence in the area sufficient to ensure that appropriate warning is provided to ships approaching the danger area.

All armed mines must be expeditiously removed or rendered harmless when the imminent danger that prompted

their emplacement has passed.”).

¹⁹⁴ HAGUE VIII art. 4 (“Neutral Powers which lay automatic contact mines off their coasts must observe the same

rules and take the same precautions as are imposed on belligerents.”).

894

mines have been laid. This notice must be communicated at once to the Governments through

the diplomatic channel.¹⁹⁵

13.11.3.1 General Obligation to Take Feasible Precautions When Using Naval

Mines. The general obligation to take feasible precautions for the protection of civilians applies

when using naval mines.¹⁹⁶ In particular, when anchored automatic contact mines are employed,

every possible precaution must be taken for the security of peaceful shipping.¹⁹⁷

13.11.3.2 International Notification When Using Armed Mines. International

notification of the location of emplaced armed mines must be made as soon as military

exigencies permit.¹⁹⁸ Such notification may be conducted through official public

announcements, communications to the United Nations, bilateral diplomatic notification, or

notices to mariners.¹⁹⁹

In particular, when anchored automatic contact mines are employed, belligerents

undertake to do their utmost to render these mines harmless within a limited time and, should

they cease to be under surveillance, to notify the danger zones as soon as military exigencies

permit, by a notice addressed to ship owners, which must also be communicated to the

Governments through the diplomatic channel.²⁰⁰

13.11.3.3 Surveillance of Minefields. Surveillance or monitoring of minefields

may be an appropriate precaution to reduce the risk of harm to peaceful vessels by permitting

warning to be given to peaceful vessels that unwittingly venture near the minefield.²⁰¹

¹⁹⁵ HAGUE VIII art. 4 (“The neutral Power must inform ship-owners, by a notice issued in advance, where automatic

contact mines have been laid. This notice must be communicated at once to the Governments through the

diplomatic channel.”).

¹⁹⁶ Refer to § 5.3.3 (Affirmative Duties to Take Feasible Precautions for the Protection of Civilians and Other

Protected Persons and Objects).

¹⁹⁷ HAGUE VIII art. 3 (“When anchored automatic contact mines are employed, every possible precaution must be

taken for the security of peaceful shipping.”).

¹⁹⁸ 2007 NWP 1-14M ¶9.2.3 (“International notification of the location of emplaced mines must be made as soon as

military exigencies permit.”); 1997 NWP 9 ¶9.2.3 (same); 1989 NWP 9 ¶9.2.3 (“International notification of the

location of emplaced armed mines must be made as soon as military exigencies permit.”).

¹⁹⁹ For example, HOWARD S. LEVIE, MINE WARFARE AT SEA 146-47 (1992) (“The mining was announced by

President Nixon on radio and television on the evening of 8 May 1972. Appropriate notification was also given to

all other nations concerned, both by a letter to the President of the United Nations Security Council, and by direct

bilateral diplomatic notification, as well as by notices to mariners. That same day (9 May 1972, in Hanoi), mines

were dropped by aircraft in Haiphong harbor (and in Cam Pha and Hon Gai harbors), three days in advance of the

mines becoming armed, thus permitting the ships in the harbor three periods of daylight in which to leave if they so

desired.”).

²⁰⁰ HAGUE VIII art. 3 (“The belligerents undertake to do their utmost to render these mines harmless within a limited

time, and, should they cease to be under surveillance, to notify the danger zones as soon as military exigencies

permit, by a notice addressed to ship owners, which must also be communicated to the Governments through the

diplomatic channel.”).

²⁰¹ Compare § 6.12.7 (Rules for Using Non-Remotely Delivered Anti-Personnel Mines Without Compliant SD/SDA

Mechanisms).

895

13.11.3.4 Recording of Minefield Locations. The location of minefields must be

carefully recorded to ensure accurate notification and to facilitate subsequent removal and/or

deactivation.²⁰²

13.11.3.5 Restrictions on Where Naval Mines May Be Placed. Mines may not be

emplaced by belligerents in neutral waters.²⁰³

Naval mines may be employed to channelize neutral shipping, but not in a manner to

deny transit passage of international straits or archipelagic sea lanes passage of archipelagic

waters by such shipping.²⁰⁴

Mining of areas of indefinite extent in international waters is prohibited. Reasonably

limited barred areas may be established by naval mines, provided neutral shipping retains an

alternate route around or through such an area with reasonable assurance of safety.²⁰⁵

13.11.3.6 Prohibition Against Mining Off Enemy Coasts and Ports Solely to

Intercept Commercial Shipping. Naval mines may not be emplaced off the coasts and ports of

the enemy with the sole objective of intercepting commercial shipping.²⁰⁶ Mining for some

other purpose would not violate this rule.²⁰⁷ For example, mines may otherwise be used in the

strategic blockade of enemy ports, coasts, and waterways, even if commercial shipping is

incidentally affected.²⁰⁸

²⁰² 2007 NWP 1-14M ¶9.2.3 (“The location of minefields must be carefully recorded to ensure accurate notification

and to facilitate subsequent removal and/or deactivation.”); 1997 NWP 9 ¶9.2.3 (same); 1989 NWP 9 ¶9.2.3 (same).

²⁰³ 2007 NWP 1-14M ¶9.2.3 (“Mines may not be emplaced by belligerents in neutral waters.”). Refer to § 15.7

(Neutral Waters).

²⁰⁴ 2007 NWP 1-14M ¶9.2.3 (“Naval mines may be employed to channelize neutral shipping, but not in a manner to

deny transit passage of international straits or archipelagic sea lanes passage of archipelagic waters by such

shipping.”); 1997 NWP 9 ¶9.2.3 (same); 1989 NWP 9 ¶9.2.3 (“Naval mines may be employed to channelize neutral

shipping, but not in a manner to impede the transit passage of international straits or archipelagic sea lanes passage

of archipelagic waters by such shipping.”).

²⁰⁵ 2007 NWP 1-14M ¶9.2.3 (“Mining of areas of indefinite extent in international waters is prohibited. Reasonably

limited barred areas may be established by naval mines, provided neutral shipping retains an alternate route around

or through such an area with reasonable assurance of safety.”); 1997 NWP 9 ¶9.2.3 (same); 1989 NWP 9 ¶9.2.3

(same).

²⁰⁶ HAGUE VIII art. 2 (“It is forbidden to lay automatic contact mines off the coast and ports of the enemy, with the

sole object of intercepting commercial shipping.”); 2007 NWP 1-14M ¶9.2.3 (“Naval mines may not be emplaced

off the coasts and ports of the enemy with the sole objective of intercepting commercial shipping, but may otherwise

be employed in the strategic blockade of enemy ports, coasts, and waterways.”); 1997 NWP 9 ¶9.2.3 (same); 1989

NWP 9 ¶9.2.3 (same).

²⁰⁷ WILLIAM H. BOOTHBY, WEAPONS AND THE LAW OF ARMED CONFLICT 283 (2009) (“If there is some other

purpose to the laying of the mines, their use in these localities is lawful. Thus, if the purpose was to intercept all

shipping, both commercial and military, the laying of the weapons would not breach this provision.”).

²⁰⁸ For example, Richard Nixon, Address to the Nation on the Situation in Southeast Asia, May 8, 1972, 1972

PUBLIC PAPERS OF THE PRESIDENTS 583, 585 (“I therefore concluded that Hanoi must be denied the weapons and

supplies it needs to continue the aggression. In full coordination with the Republic of Vietnam, I have ordered the

following measures which are being implemented as I am speaking to you. All entrances to North Vietnamese ports

will be mined to prevent access to these ports and North Vietnamese naval operations from these ports. … Countries

896

13.11.3.7 Neutralization of Naval Mines. Anchored mines must become harmless

as soon as they have broken their moorings.²⁰⁹ In particular, it is forbidden to lay anchored

automatic contact mines that do not become harmless as soon as they have broken loose from

their moorings.²¹⁰

Unanchored mines not otherwise affixed or imbedded on the ocean floor must become

harmless within an hour after loss of control over them.²¹¹ In particular, it is forbidden to lay

unanchored (i.e., free-floating) automatic contact mines, except when they are so constructed as

to become harmless one hour at most after the person who laid them ceases to control them.²¹²

13.11.4 Post-Conflict Naval Demining Obligations. The removal of naval mines at the

end of the conflict may be the subject of specific agreements among States.²¹³

At the close of a war to which Hague VIII is applicable, Parties to Hague VIII have an

obligation to remove the naval mines that they had laid, each State removing its own mines.²¹⁴

As regards anchored automatic contact mines laid by one of the belligerents off the coast of the

other, their position must be notified to the other party by the State that laid them, and each State

must proceed with the least possible delay to remove the mines in its own waters.²¹⁵

with ships presently in North Vietnamese ports have already been notified that their ships will have three daylight

periods to leave in safety. After that time, the mines will become active and any ships attempting to leave or enter

these ports will do so at their own risk.”).

²⁰⁹ 2007 NWP ¶9.2.3 (“Anchored mines must become harmless as soon as they have broken their moorings.”); 1997

NWP 9 ¶9.2.3 (same); 1989 NWP 9 ¶9.2.3 (same).

²¹⁰ HAGUE VIII art. 1 (“It is forbidden … 2. To lay anchored automatic contact mines which do not become harmless

as soon as they have broken loose from their moorings;”).

²¹¹ 2007 NWP ¶9.2.3 (“Unanchored mines not otherwise affixed or imbedded in the bottom must become harmless

within an hour after loss of control over them.”); 1997 NWP 9 ¶9.2.3 (same); 1989 NWP 9 ¶9.2.3 (same).

²¹² HAGUE VIII art. 1 (“It is forbidden … 1. To lay unanchored automatic contact mines, except when they are so

constructed as to become harmless one hour at most after the person who laid them ceases to control them;”).

²¹³ For example, Protocol to the Agreement on Ending the War and Restoring Peace in Vietnam Concerning the

Removal, Permanent Deactivation, or Destruction of Mines in the Territorial Waters, Ports, Harbors, and Waterways

of the Democratic Republic of Vietnam, Jan. 27, 1973, 24 U.S.T. 1, art. 1 (“The United States shall clear all the

mines it has placed in the territorial waters, ports, harbors, and waterways of the Democratic Republic of Vietnam.

This mine clearing operation shall be accomplished by rendering the mines harmless through removal, permanent

deactivation, or destruction.”).

²¹⁴ HAGUE VIII art. 5 (“At the close of the war, the Contracting Powers undertake to do their utmost to remove the

mines which they had laid, each Power removing its own mines.”).

²¹⁵ HAGUE VIII art. 5 (“As regards anchored automatic contact mines laid by one of the belligerents off the coast of

the other, their position must be notified to the other party by the Power which laid them, and each Power must

proceed with the least possible delay to remove the mines in its own waters.”).

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13.12 TORPEDOES

It is forbidden to use torpedoes that do not become harmless when they miss their

mark.²¹⁶ Such torpedoes may become a hazard to innocent shipping, and therefore torpedoes

must be designed to become harmless when they have missed their mark.

For example, torpedoes have been designed to become harmless upon completion of their

propulsion run, such as by sinking to the bottom.

13.12.1 Torpedoes - Notes on Terminology. In the 19th century, the term “torpedo” was

used to refer to any explosive munition that operated by contact against the hull of a ship,

including relatively stationary munitions that, in modern parlance, would be called mines.²¹⁷

However, by the time of the 1907 Hague VIII Convention, the term “torpedo” was used in the

modern sense to refer to munitions that propelled through the water.²¹⁸

13.13 DECEPTION BY NAVAL FORCES, INCLUDING THE USE OF ENEMY OR NEUTRAL FLAGS

In general, the rules concerning good faith, ruses, and perfidy also apply to naval

warfare.²¹⁹ For example, it would be prohibited for a belligerent warship to convey falsely the

appearance of a hospital ship.²²⁰ On the other hand, a variety of deceptions are not prohibited,

including camouflage, deceptive lighting, disguised electronic signatures, and dummy ships,

among others.²²¹

²¹⁶ HAGUE VIII art. 1 (“It is forbidden … 3. To use torpedoes which do not become harmless when they have missed

their mark.”).

²¹⁷ For example, TAMARA MOSER MELIA, DAMN THE TORPEDOES: A SHORT HISTORY OF U.S. NAVAL MINE

COUNTERMEASURES, 1777-1991, 3 (1991) (“At high tide on the morning of 5 August Farragut entered the bay.

Farragut’s officers had persuaded him to allow the sloop Brooklyn, hastily rigged with a rudimentary torpedo catcher

on the bowsprit, to lead the advance in place of Farragut’s flagship, Hartford. Contrary to Farragut’s orders,

monitor Tecumseh moved west of the red buoy where it struck and detonated one of the newly placed mines. As

Tecumseh quickly went down, Brooklyn suddenly stopped and backed, stalling the fleet’s advance. High in

Hartford’s rigging Farragut watched Tecumseh sink and Brooklyn hesitate. From Hartford’s poop deck Lieutenant

Watson heard the admiral’s exchange with Brooklyn: ‘Farragut hailed again and all that could be distinguished of

her reply was something about torpedoes. ‘Damn the torpedoes!’ he instantly shouted, ordering Hartford’s captain

‘Full speed ahead, Drayton.’’”).

²¹⁸ A. PEARCE HIGGINS, THE HAGUE PEACE CONFERENCES AND OTHER INTERNATIONAL CONFERENCES CONCERNING

THE LAWS AND USAGES OF WAR. TEXT OF CONVENTIONS WITH COMMENTARIES 328 (1909) (“The word ‘torpille’

until recently appears to have meant any sort of receptacle containing an explosive intended to operate against the

hull of a ship by contact either on or below the water line. Thus, there were torpilles fizes, torpilles mouillees,

torpilles mobiles, and finally torpilles automobiles. It would appear that latterly the word has come to mean only

‘automobile torpedo,’ e.g. in the Convention now under consideration the word ‘mine’ is used when an automatic

torpedo is not implied.”).

²¹⁹ Refer to § 5.21 (Overview of Good Faith, Perfidy, and Ruses).

²²⁰ Refer to § 5.24.2 (Distinctive Emblems of the Geneva Conventions (e.g., Red Cross)); § 7.12.3 (Distinctive

Marking and Other Identification of Hospital Ships and Coastal Rescue Craft).

²²¹ Refer to § 5.25.2 (Examples of Ruses).

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The rules concerning deception by belligerent warships, especially with respect to the

flying of neutral flags or with respect to disguise as merchant vessels, may be considered more

permissive than similar situations in land warfare.²²²

13.13.1 Belligerent Warship’s Use of False Colors and Other Disguises. In particular,

according to custom, it is permissible for a belligerent warship to use false colors and to disguise

her outward appearance in other ways in order to deceive an enemy, provided that before going

into action such warship shows her true colors.²²³

For example, a belligerent warship may fly enemy or neutral colors and display enemy or

neutral markings in order to deceive the enemy into believing the vessel is of enemy or neutral

nationality or is not a warship.²²⁴ Such deceptions may be used in order to facilitate the

approach of enemy vessels or to escape enemy vessels.²²⁵

Warships, however, may not seek to claim falsely the status of vessels that are exempt

from capture or destruction. These vessels include: (1) cartel vessels; (2) hospital ships; (3)

vessels charged with religious, non-military scientific, or philanthropic missions; (4) vessels

granted safe conduct; and (5) small coastal fishing vessels and small boats engaged in local

coastal trade.²²⁶

²²² Refer to § 5.24.1 (Signs, Emblems, or Uniforms of a Neutral or Non-Belligerent State).

²²³ See, e.g., 2007 NWP 1-14M ¶12.3.1 (“Under the customary international law of naval warfare, it is permissible

for a belligerent warship to fly false colors and disguise its outward appearance in other ways in order to deceive the

enemy into believing the vessel is of neutral nationality or is other than a warship. However, it is unlawful for a

warship to go into action without first showing her true colors.”); 2007 NWP 1-14M ¶12.5.1 (“Naval surface and

subsurface forces may fly enemy colors and display enemy markings to deceive the enemy. Warships must,

however, display their true colors prior to an actual armed engagement.”); 1955 NWIP 10-2 ¶640a (“In particular,

according to custom, it is permissible for a belligerent warship to use false colors and to disguise her outward

appearance in other ways in order to deceive an enemy, provided that prior to going into action such warship shows

her true colors.”).

²²⁴ For example, TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 140 footnote 37 (“During World War II the

Germans enjoyed a measurable degree of success through the skillful disguise they provided for their armed raiders.

… The tactics of the armed raiders were to reveal their true identity only after having come within close enough

range to overwhelm the victim (usually armed enemy merchant vessels) by surprise.— One of the most notable

actions involving these armed raiders took place in November 1941 between the Australian cruiser Sydney and the

German armed raider Kormoran. The disguised raider, when approached by the Sydney, identified herself as a

Dutch merchant vessel. Before the Sydney could establish the truth or falsity of her claimed identity the Kormoran

cast off her disguise and opened fire at a distance of 2,000 yards. As a result of the action the Sydney was destroyed

with complete loss of officers and crew.”); LAUTERPACT, II OPPENHEIM’S INTERNATIONAL LAW 510 (§211) (“On the

other hand, the following is a perfectly legitimate ruse which is reported to have occurred during the World War: at

the end of October 1914, the German cruiser Emden, hiding her identity by rigging up a dummy fourth funnel and

flying the Japanese flag, passed the guardship of the harbor Penang in the Malay States, made no reply to its signals,

came down at full speed on the Russian cruiser Zhemshug, and then, after lowering the Japanese flag and hoisting

the German flag, opened fire and torpedoed her.”).

²²⁵ LAUTERPACT, II OPPENHEIM’S INTERNATIONAL LAW 509 (§211) (“As regards the use of a false flag, it is by most

writers considered perfectly lawful for a man-of-war to use a neutral or enemy flag (1) when chasing an enemy

vessel, (2) when trying to escape, and (3) for the purpose of drawing an enemy vessel into action. On the other

hand, it is universally agreed that, immediately before an attack, a vessel must fly her national flag.”).

²²⁶ Refer to § 13.6 (Enemy Vessels Exempt From Capture or Destruction).

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XIV - Air and Space Warfare

Chapter Contents

14.1 Introduction

14.2 Legal Boundaries of Airspace

14.3 Aircraft Status

14.4 Status of Aircrew on Military Aircraft

14.5 Measures Short of Attack: Interception, Diversion, and Capture

14.6 Belligerent Control of Aviation in the Immediate Vicinity of Hostilities

14.7 Airspace Zones

14.8 Attacks Against Military Objectives in the Air

14.9 Air Attacks Against Military Objectives on the Ground

14.10 International Law And Warfare in Outer Space

14.1 INTRODUCTION

This Chapter addresses the international law applicable to U.S. air and space operations

during international armed conflict. This Chapter also discusses the application to air operations

of some of the law of war rules discussed elsewhere in this manual.

Air Force publications have provided discussion of other aspects of public international

law relating to air operations, including discussion of rules applicable during peacetime.¹

14.1.1 Application of the 1944 Chicago Convention With Respect to Military Aircraft

and With Respect to States’ Rights During Armed Conflict. The 1944 Chicago Convention

primarily addresses States’ obligations regarding international civil aviation.² The 1944 Chicago

Convention does not restrict State action during war.³ In addition, the 1944 Chicago Convention

generally is not applicable to State aircraft.⁴ However, the 1944 Chicago Convention imposes

requirements with respect to entry by State aircraft into foreign airspace and with respect to the

issue of due regard for the safety of navigation of civil aircraft.⁵

14.1.1.1 1944 Chicago Convention and Freedom of Action of States During

Armed Conflict. According to Article 89 of the 1944 Chicago Convention, “[i]n case of war, the

provisions of this Convention shall not affect the freedom of action of any of the contracting

¹ See, e.g., Department of the Air Force, The Judge Advocate General’s School, Air Force Operations and The Law

(3rd ed., 2014); 1976 AIR FORCE PAMPHLET 110-31.

² 1944 CHICAGO CONVENTION preamble (“THEREFORE, the undersigned governments having agreed on certain

principles and arrangements in order that international civil aviation may be developed in a safe and orderly manner

and that international air transport services may be established on the basis of equality of opportunity and operated

soundly and economically; Have accordingly concluded this Convention to that end.”).

³ Refer to § 14.1.1.1 (1944 Chicago Convention and Freedom of Action of States During Armed Conflict).

⁴ Refer to § 14.1.1.2 (1944 Chicago Convention and Military Aircraft or Other State Aircraft).

⁵ Refer to § 14.1.1.3 (Requirement for State Consent Prior to Entry by Foreign State Aircraft); § 14.1.1.4 (Due

Regard for the Safety of Navigation of Civil Aircraft).

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States affected, whether as belligerents or as neutrals.”⁶ Article 89 may be understood as an

example, reflected in this case in the Convention, of the application of the general principle that

the law of war, as a body of law specially adapted to the circumstances of armed conflict, is the

controlling body of law with respect to armed conflict.⁷ Under Article 89, a State’s rights under

the law of war (and the law of neutrality) would prevail in the event of conflict with obligations

under the 1944 Chicago Convention.

The provisions of the 1944 Chicago Convention may be relevant during armed conflict

insofar as they articulate restrictions that continue to apply to civil aircraft. For example, neutral

civil aircraft engaged in international navigation would still be required to seek permission from

a foreign neutral State before carrying munitions of war or implements of war through that

neutral State’s airspace.⁸

The 1944 Chicago Convention’s requirements with respect to entry by State aircraft into

foreign airspace and with respect to the issue of due regard for the safety of navigation of civil

aircraft are discussed below.⁹

14.1.1.2 1944 Chicago Convention and Military Aircraft or Other State Aircraft.

The 1944 Chicago Convention provides generally that the Convention “shall be applicable only

to civil aircraft, and shall not be applicable to state aircraft.”¹⁰ State aircraft include aircraft used

in military service.¹¹ The United States has made statements interpreting this provision of the

1944 Chicago Convention.¹²

⁶ 1944 CHICAGO CONVENTION art. 89 (“In case of war, the provisions of this Convention shall not affect the freedom

of action of any of the contracting States affected, whether as belligerents or as neutrals.”).

⁷ Refer to § 1.3.2 (The Law of War’s Relationship to Other Bodies of Law).

⁸ See, e.g., 1944 CHICAGO CONVENTION art. 35(a) (“(a) No munitions of war or implements of war may be carried in

or above the territory of a State in aircraft engaged in international navigation, except by permission of such State.

Each State shall determine by regulations what constitutes munitions of war or implements of war for the purposes

of this Article, giving due consideration, for the purposes of uniformity, to such recommendations as the

International Civil Aviation Organization may from time to time make.”).

⁹ Refer to § 14.1.1.3 (Requirement for State Consent Prior to Entry by Foreign State Aircraft); § 14.1.1.4 (Due

Regard for the Safety of Navigation of Civil Aircraft).

¹⁰ 1944 CHICAGO CONVENTION art. 3(a) (“This Convention shall be applicable only to civil aircraft, and shall not be

applicable to state aircraft.”).

¹¹ Refer to § 14.3.1 (State Versus Civil Aircraft).

¹² See, e.g., Department of State Airgram CA-8085, Feb. 13, 1964, quoting U.S. Inter-Agency Group on

International Aviation (IGIA) Doc. 88/1/1C, MS, Department of State, file POL 31 U.S., IX WHITEMAN’S DIGEST

430-31 (“The Chicago Convention expressly excludes state aircraft from its scope and thus from the scope of ICAO

[International Civil Aviation Organization] responsibility. The United States intends that its state aircraft will

follow the ICAO procedures set forth in Annex 2 [“Rules of the Air”] to the greatest extent practicable; however, the

United States considers that state aircraft of any nation are subject to control and regulation exclusively by that

nation (unless operating within airspace over which another nation has sovereignty). With respect to State aircraft,

contracting States need not undertake any commitment, and the United States does not undertake any commitment,

to other nations as to the rules and regulations which any specific state aircraft or class of state aircraft will follow,

except when issuing regulations for their state aircraft, that ‘they will have due regard for the safety of navigation of

civil aircraft’ (Article 3(d), Chicago Convention).”).

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The 1944 Chicago Convention, however, imposes obligations with respect to entry into

foreign airspace by State aircraft and an obligation with respect to State aircraft and the safety of

navigation of civil aircraft.¹³

14.1.1.3 Requirement for State Consent Prior to Entry by Foreign State Aircraft.

The 1944 Chicago Convention provides that State aircraft (which include military aircraft) are

not permitted to enter the airspace of another State without that State’s consent.¹⁴

During armed conflict, the requirement for a State’s consent to entry into its airspace

would generally continue to apply with respect to neutral military aircraft seeking to enter the

airspace of foreign States.

This requirement, however, clearly would not apply to belligerent military aircraft

conducting operations in enemy airspace.

The requirement for a State’s consent to entry into its airspace may be characterized as

applicable with respect to belligerent military aircraft and a neutral State’s airspace; however,

even if belligerent military aircraft enter neutral airspace with that neutral State’s consent, such

entry may involve violations of neutrality.¹⁵

There are exceptions to the requirement for State consent to entry into its airspace by

State aircraft in certain cases of violations of neutrality.¹⁶

There is an exception during peacetime to the requirement for a State’s consent to entry

into its airspace by foreign State aircraft when such entry is due to distress and there is no

reasonable safe alternative.¹⁷

14.1.1.4 Due Regard for the Safety of Navigation of Civil Aircraft. The 1944

Chicago Convention also provides that “[t]he contracting States undertake, when issuing

regulations for their state aircraft, that they will have due regard for the safety of navigation of

¹³ Refer to § 14.1.1.3 (Requirement for State Consent Prior to Entry by Foreign State Aircraft); § 14.1.1.4 (Due

Regard for the Safety of Navigation of Civil Aircraft).

¹⁴ 1944 CHICAGO CONVENTION art. 3(c) (“No state aircraft of a contracting State shall fly over the territory of

another State or land thereon without authorization by special agreement or otherwise, and in accordance with the

terms thereof.”).

¹⁵ Refer to § 15.10.2 (Prohibition on Entry by Belligerent Military Aircraft Into Neutral Airspace).

¹⁶ Refer to § 15.4.2 (Belligerent Use of Self-Help When Neutral States Are Unable or Unwilling to Prevent

Violations of Neutrality).

¹⁷ U.S. Response to Chinese Legal Views, 2001 DIGEST OF UNITED STATES PRACTICE IN INTERNATIONAL LAW 703,

708 (“—Although we recognize that military aircraft normally require permission to enter the territorial airspace of

another nation, international law recognizes a right of entry for foreign aircraft, state or civil, in circumstances such

as these when such entry is due to distress and there is no reasonable safe alternative (Footnote 3 below). —

Notwithstanding the ordinary rules requiring consent, a peacetime right to enter in distress for military aircraft is

consistent with established international practice.

— Such a right is clearly inferable both from analogous situations

in which such a right exists (e.g., for civil aircraft under Article 25 of the Chicago Convention) and from basic

humanitarian considerations.”).

902

civil aircraft.”¹⁸ Assuming that an obligation to exercise due regard would be applicable during

armed conflict, what regard would be due in any particular set of circumstances would depend on

military necessity, and other principles and rules of the law of war, which are specially adapted

to the circumstances of armed conflict. For example, the use of force against enemy civil aircraft

that constitute military objectives and thus may be made the object of attack under the law of war

would not be prohibited.¹⁹

As reflected in Article 89 of the 1944 Chicago Convention, the Convention does not

restrict the freedom of action of States as belligerents or neutrals.²⁰ Nonetheless, as a practical

matter, modern air warfare is often conducted in complex airspace, and U.S. forces have

routinely and intensively coordinated flight operations with national civil aviation authorities.

This coordination is important for a variety of purposes, including ensuring mission

accomplishment, avoiding fratricide and mid-air collisions, and ensuring the safety of

international civil aviation. DoD policy has required that, in the event of combat operations

during armed conflict, aircraft commanders, consistent with military necessity, take measures to

minimize hazards to civil air or surface traffic.²¹

Similarly, under the law of the sea, military operations must be conducted with due

regard for the high seas freedom of overflight in international airspace.²²

14.1.2 Past Attempts to Conclude Treaties About Air Warfare. Initial attempts to

conclude agreements on the law of war governing means and methods in the air context were

made during the 1899 and 1907 Hague Peace Conferences, before air power had become a

significant factor in warfare. Extensive efforts were made in 1922-23 to adopt a code of laws

specifically applicable only to air warfare; however, the proposed rules were not ratified by any

State.²³ The United States has not ratified a treaty applicable solely to air operations during

armed conflict, although the United States has ratified treaties that have included specific

¹⁸ 1944 CHICAGO CONVENTION art. 3(d) (“The contracting States undertake, when issuing regulations for their state

aircraft, that they will have due regard for the safety of navigation of civil aircraft.”).

¹⁹ Refer to § 14.8.3 (Attacks Against Civil Aircraft).

²⁰ Refer to § 14.1.1.1 (1944 Chicago Convention and Freedom of Action of States During Armed Conflict).

²¹ DOD INSTRUCTION 4540.01, Use of International Airspace by U.S. Military Aircraft and for Missile/Projectile

Firings, ¶4.2.3 (Mar. 28, 2007) (“In the event of combat operations in time of war, armed conflict, national

emergency, situations requiring self-defense, or similar military contingencies, aircraft commanders shall, consistent

with military necessity, take measures to minimize hazards to civil air or surface traffic. Such actions shall be of no

greater extent or duration than required by military necessity.”); DOD DIRECTIVE 4540.1, Use of Airspace by U.S.

Military Aircraft and Firings Over the High Seas, ¶6b (Jan. 13, 1981) (“In the event of combat operations in time of

war, armed conflict, national emergency, situations requiring self-defense, or similar military contingencies,

departure from the operating procedures in this Directive may be required. In all such instances, however, all

possible precautions shall be taken to minimize any hazard to the safety of other air and surface traffic and departure

from procedures set forth in this Directive shall be of no greater extent or duration than is required to meet the

contingency.”).

²² Refer to § 13.1.1 (The Law of the Sea During Armed Conflict).

²³ Refer to § 19.11 (1923 Hague Air and Radio Rules).

903

references to aspects of war in the air, such as protection for medical aircraft in the 1949 Geneva

Conventions.²⁴

14.2 LEGAL BOUNDARIES OF AIRSPACE

The legal classifications of airspace may be relevant to the application of the law of war

and therefore may affect military operations during armed conflict by:

• determining whether airspace is neutral airspace;²⁵

• determining the authority that a belligerent State has with respect to neutral aircraft in an

area; or

• determining the authority that a neutral State has with respect to belligerent aircraft in an

area.

14.2.1 Lateral Boundaries of Airspace. The lateral boundaries of the airspace are

determined by the status of the land or water directly beneath them.

Airspace is often divided between national airspace (i.e., airspace over a State’s land

territory, internal waters, territorial seas, and archipelagic waters), which is subject to the

sovereignty of a State, and international airspace, which is not subject to the sovereignty of any

State.²⁶ In addition, special rules apply to international straits and archipelagic sea lanes.²⁷

The division between national airspace and international airspace is similar to the

division between national waters and international waters.²⁸ One notable distinction, however,

is that aircraft do not enjoy the same right of innocent passage over territorial seas that ships

enjoy through territorial seas.²⁹

14.2.1.1 National Airspace. Every State has complete and exclusive sovereignty

over the airspace above its territory.³⁰ In other words, a State has sovereignty over the airspace

that is above land or waters that are subject to its sovereignty.³¹ Thus, a State’s national airspace

includes:

²⁴ Refer to § 7.14 (Military Medical Aircraft); § 7.19 (Civilian Medical Aircraft).

²⁵ Refer to § 15.10 (Neutral Airspace).

²⁶ Refer to § 14.2.1.1 (National Airspace); § 14.2.1.2 (International Airspace).

²⁷ Refer to § 15.8 (Passage of Belligerent Vessels and Aircraft Through International Straits and Archipelagic Sea

Lanes).

²⁸ Refer to § 13.2.2 (National Waters); § 13.2.3 (International Waters).

²⁹ Refer to § 13.2.2.4 (Innocent Passage of Foreign Vessels Through Territorial Seas and Archipelagic Waters).

³⁰ 1944 CHICAGO CONVENTION art. 1 (“The contracting States recognize that every State has complete and exclusive

sovereignty over the airspace above its territory.”). Cf. 49 U.S.C. § 40103 (a)(1) (“The United States Government

has exclusive sovereignty of airspace of the United States.”).

³¹ See, e.g., 1944 CHICAGO CONVENTION art. 2 (“For the purposes of this Convention the territory of a State shall be

deemed to be the land areas and territorial waters adjacent thereto under the sovereignty, suzerainty, protection or

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• airspace over that State’s land territory, including its internal waters;³²

• airspace over that State’s territorial sea;³³ and

• airspace over that State’s archipelagic sea.³⁴

14.2.1.2 International Airspace. International airspace may be understood as all

airspace that is not subject to the sovereignty of any State, including:³⁵

• airspace over States’ contiguous zones;³⁶

• airspace over States’ Exclusive Economic Zones;³⁷ and

• airspace over the high seas.³⁸

14.2.2 Vertical Boundary Between Airspace and Outer Space. A State’s sovereignty over

its airspace does not extend to outer space, which is not subject to the sovereignty of any State.³⁹

It is generally accepted that orbiting objects are in outer space.⁴⁰ The United States has

expressed the view that there is no legal or practical need to delimit or otherwise define a

specific boundary between airspace and outer space.⁴¹

mandate of such State.”); Convention on the Territorial Sea and Contiguous Zone, art. 2, Apr. 29, 1958, 516 UNTS

205, 208 (“The sovereignty of a coastal State extends to the air space over the territorial sea as well as to its bed and

subsoil.”). Consider LOS CONVENTION art. 2(2) (“This sovereignty extends to the air space over the territorial sea

as well as to its bed and subsoil.”); LOS CONVENTION art. 49(2) (“This sovereignty extends to the air space over the

archipelagic waters, as well as to their bed and subsoil, and the resources contained therein.”).

³² Refer to § 13.2.2.1 (Internal Waters).

³³ Refer to § 13.2.2.2 (Territorial Seas).

³⁴ Refer to § 13.2.2.3 (Archipelagic Waters).

³⁵ See, e.g., DOD DIRECTIVE 4500.54E, DoD Foreign Clearance Program (FCP), Glossary (Dec. 28, 2009)

(“international airspace. All airspace seaward of coastal states’ national airspace, including airspace over

contiguous zones, exclusive economic zones, and the high seas. International airspace is open to all aircraft of all

nations. Military aircraft may operate in such areas free of interference or control by the coastal state.”).

³⁶ Refer to § 13.2.3.2 (Contiguous Zones).

³⁷ Refer to § 13.2.3.3 (Exclusive Economic Zones (EEZs)).

³⁸ Refer to § 13.2.3.4 (High Seas).

³⁹ Refer to § 14.10.1 (Classification of Outer Space).

⁴⁰ See, e.g., Department of the Air Force, The Judge Advocate General’s School, Air Force Operations and The

Law, 85 (3rd ed., 2014) (“According to this approach, the upper limit to airspace is above the highest altitude at

which an aircraft can fly and below the lowest possible perigee of an earth satellite in orbit. The result is that

anything in orbit or beyond can safely be regarded as being in outer space.”); 2007 NWP 1-14M ¶¶1.10, 2.11.1

(“The upper limit of airspace subject to national jurisdiction has not been authoritatively defined by international

law. International practice has established that airspace terminates at some point below the point at which artificial

satellites can be placed in orbit without free-falling to earth. Outer space begins at that undefined point. …

Although there is no legally defined boundary between the upper limit of national airspace and the lower limit of

outer space, international law recognizes freedom of transit by man-made space objects at earth orbiting altitude and

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14.2.3 Flight Information Regions. Flight Information Regions (FIRs) are areas of

airspace allocated by the International Civil Aviation Organization (ICAO). Every portion of

airspace belongs to a defined flight information region. Within each flight information region, a

flight information service and an alerting service are provided by the national authorities

responsible for air traffic control. These services are the most basic levels of air traffic service,

and they provide information to aviators necessary for the safe and efficient conduct of flights.⁴²

A flight information region normally encompasses substantial areas of international

airspace and does not necessarily reflect international or national airspace borders.⁴³

beyond. A generally acceptable definition is that outer space begins at the undefined upper limit of the earth’s

airspace and extends to infinity.”); 2006 AUSTRALIAN MANUAL ¶8-2 (“While views differ as to the precise vertical

and horizontal extent of airspace, for practical purposes, it can be said that the upper limit to a state’s rights in

airspace is above the highest altitude at which an aircraft can fly and below the lowest possible perigee of an earth

satellite in orbit. The result is that anything in orbit or beyond can safely be regarded as in outer space.”); 2004 UK

MANUAL ¶12.13 (“Views differ as to the precise vertical and horizontal extent of airspace. For practical purposes, it

can be said that the upper limit to a state’s rights in airspace is above the highest altitude of what an aircraft can fly

and below the lowest possible perigee of an earth satellite in orbit. The result is that anything in orbit or beyond can

safely be regarded as in outer space.”).

⁴¹ Kenneth Hodgkins, U.S. Advisor to the United Nations, Legal Subcommittee (LSC) of the United Nations

Committee on the Peaceful Uses of Outer Space (COPUOS) 719th Meeting [unedited transcript] (Apr. 8, 2005) (“As

we have stated on previous occasions, the United States is firmly of the view that there is no need to seek a legal

definition or delimitation for outer space. The current framework has presented no practical difficulties and, indeed,

activities in outer space are flourishing. Given this situation, an attempt to define or delimit outer space would be an

unnecessary theoretical exercise that could potentially complicate existing activities and that might not be able to

anticipate continuing technological developments. The current framework has served us well and we should

continue to operate under this framework until there is a demonstrated need and a practical basis for developing a

definition or delimitation.”); Stephen Mathias, U.S. Advisor to the United Nations, U.S. Statements on Specific

Agenda Items before the Legal Subcommittee of the Committee on the Peaceful Uses of Outer Space (2003) (“At this

time, the United States remains convinced that there is no need to seek a legal definition of delimitation for outer

space. Activities in outer space and in airspace are flourishing and have raised no practical need for a definition or

limitation between the spheres. In the absence of a real need, any attempt to develop a definition would be ill-

advised as there would be no experience to call upon in agreeing upon any particular definition or delimitation.”);

U.S. Statement before the Legal Subcommittee of the United Nations Committee on the Peaceful Uses of Outer

Space regarding the Definition and Delimitation of Outer Space and the Character and Utilization of the

Geostationary Orbit, Apr. 4, 2001, 2001 DIGEST OF UNITED STATES PRACTICE IN INTERNATIONAL LAW 721 (“Our

position continues to be that defining or delimiting outer space is not necessary. No legal or practical problems have

arisen in the absence of such a definition. On the contrary, the differing legal regimes applicable in respect of

airspace and outer space have operated well in their respective spheres. The lack of a definition or delimitation of

outer space has not impeded the development of activities in either sphere. … It would be dangerous for the Legal

Subcommittee to agree to an artificial line between air space and outer space, when it cannot predict the

consequences of such a line.”).

⁴² Information Provided to U.S. Embassies in Rangoon and New Delhi Regarding Transit Through Flight

Information Regions and International Airspace, May 2007, 2007 DIGEST OF UNITED STATES PRACTICE IN

INTERNATIONAL LAW 635, 636 (“A Flight Information Region, or FIR, is simply an area over which a civil aviation

authority has responsibility for provision of flight information services. FIRs are allocated to coastal states by the

International Civil Aviation Organization (ICAO) to facilitate the safety of civil aviation. Some FIRs encompass

both national and international airspace. Civil aviation authorities may confuse responsibility for and authority over

civil aviation in a FIR for sovereignty over the area.”).

⁴³ DOD DIRECTIVE 4500.54E, DoD Foreign Clearance Program (FCP), Glossary (Dec. 28, 2009) (“flight

information region. An airspace of defined dimensions within which flight information service and alerting service

906

Under Article 3 of the 1944 Chicago Convention, flight information region rules do not

apply to State aircraft, including military aircraft, and military aircraft are free to operate in

international airspace without the consent of or notice to coastal State authorities.⁴⁴ Thus, for

example, a flight information region could not limit the rights of belligerent military aircraft

during armed conflict.

14.2.4 Air Defense Identification Zone (ADIZ). In general terms, an ADIZ is an area of

airspace over land or water in which the ready identification, location, and control of aircraft

may be required in the interests of national security.⁴⁵ The United States has established

ADIZs.⁴⁶

14.2.4.1 Establishment of an ADIZ. The legal basis for a State to establish an

ADIZ is its right to establish conditions and procedures for entry into its national airspace.⁴⁷

are provided. A flight information region normally encompasses substantial areas of international airspace and does

not reflect international or national airspace borders. Responsibility for flight information region management is not

the same as territorial authority; therefore, state aircraft are not to request aircraft diplomatic clearance to enter a

flight information region if the aircraft will not enter national airspace. The International Civil Aviation

Organization establishes flight information regions in accordance with the Convention on International Civil

Aviation. Civil aviation authorities of designated nations administer them pursuant to International Civil Aviation

Organization authority, rules, and procedures.”).

⁴⁴ Information Provided to U.S. Embassies in Rangoon and New Delhi Regarding Transit Through Flight

Information Regions and International Airspace, May 2007, 2007 DIGEST OF UNITED STATES PRACTICE IN

INTERNATIONAL LAW 635-36 (“A coastal state may establish a FIR in international airspace consistent with the

requirements of the 1944 Convention on International Civil Aviation (Chicago Convention), to which your country

is a party; however, under Article 3 of that convention, FIR rules do not apply to state aircraft, including military

aircraft. State aircraft, including military aircraft, operating in international airspace (whether within or outside a

FIR) are free to operate without the consent of or notice to coastal state authorities and are not subject to the

jurisdiction or control of the ATC authorities of those states. No notice to, clearance from, or approval of a coastal

state is required to exercise such freedoms of navigation and overflight. The United States reaffirms its navigation

and overflight rights in international airspace.”).

⁴⁵ 14 CODE OF FEDERAL REGULATIONS § 99.3 (“Air defense identification zone (ADIZ) means an area of airspace

over land or water in which the ready identification, location, and control of all aircraft (except for Department of

Defense and law enforcement aircraft) is required in the interest of national security.”).

⁴⁶ See, e.g., Ian E. Rinehart & Bart Elias, China’s Air Defense Identification Zone (ADIZ), 2 (Congressional

Research Service, Jan. 30, 2015) (“In 1948, the U.S. Air Force designated several offshore areas as ‘active defense

areas’ or ‘defense zones.’ From these, the first ADIZs in the world were established in 1950, under an Executive

order directing the Secretary of Commerce to exercise security control over aircraft. Various defense zones were

redesignated as ADIZs (over Atlantic, Pacific, and Gulf of Mexico waters[)] the Alaska ADIZ, the Guam ADIZ, and

the Hawaii ADIZ, are codified in Title 14, Part 99, of the Code of Federal Regulations, along with the procedural

requirements for flights operating in these designated areas. They are predominantly located over water and

typically do not extend to the shore, leaving a narrow strip of sovereign airspace parallel to the coastline that is not

within the ADIZ.”); 1955 NWIP 10-2 ¶422c endnote 16 (“It is apparent that the potential threat to the security of

states presented by aircraft is considerably greater than the potential threat presented by vessels. However, there has

not yet emerged a recognized practice of ‘contiguous air space zones,’ analogous to contiguous zones established on

the high seas (see paragraph 413d), enabling states to exercise certain legal controls over aircraft flying outside

territorial air space. The present system of Air Defense Identification Zones (ADIZ) employed by the United States

extends to the air space above the open sea, and is limited to the purpose of identifying aircraft.”).

⁴⁷ See, e.g., 2007 NWP 1-14M ¶2.7.2.3 (“International law does not prohibit nations from establishing air defense

identification zones (ADIZ) in the international airspace adjacent to their territorial airspace. The legal basis for

907

The establishment of an ADIZ by a State does not constitute a claim to international

airspace as its own. The ADIZ is merely a reference point for the initiation of identification

procedures for aircraft on a course to enter national airspace.⁴⁸

Because the establishment of an ADIZ by a State that extends to international airspace

does not confer sovereignty over that airspace, the ADIZ, and its implementing regulations and

operational practices, must respect the rights of other States to use international airspace.

The United States does not recognize the right of a State to apply its ADIZ laws and

regulations to foreign aircraft, either civil aircraft or State aircraft, if those aircraft do not intend

to enter the national airspace of that State.⁴⁹

14.2.4.2 Failure to Comply With Identification Requirements. Failure by an

aircraft to identify itself once it enters an ADIZ does not, of itself, entitle the declaring State to

use force against that aircraft, although it may subject the aircraft to interception.⁵⁰ Depending

on the circumstances, a persistent failure to comply with instructions may be evidence that the

aircraft, in fact, poses a threat to the declaring State.⁵¹

Establishment of an ADIZ, like other warning zones, does not relieve the proclaiming

State of its obligations under applicable international law, such as its obligation under the law of

war to refrain from attacking aircraft that do not constitute lawful military objectives, or its

obligation to refrain from attacks against civil aircraft under peacetime international law.⁵²

ADIZ regulations is the right of a nation to establish reasonable conditions of entry into its territory. Accordingly,

an aircraft approaching national airspace can be required to identify itself while in international airspace as a

condition of entry approval.”); 1976 AIR FORCE PAMPHLET 110-31 ¶2-1g (“Civil aircraft on a course to penetrate

United States airspace are required to identify themselves upon entry into the [Air Defense Identification] zone.

This requirement is based on the right of every state to establish conditions and procedures for entry into its

airspace.”). See also 1944 CHICAGO CONVENTION art. 11 (“Subject to the provisions of this Convention, the laws

and regulations of a contracting State relating to the admission to or departure from its territory of aircraft engaged

in international air navigation, or to the operation and navigation of such aircraft while within its territory, shall be

applied to the aircraft of all contracting States without distinction as to nationality, and shall be complied with by

such aircraft upon entering or departing from or while within the territory of that State.”).

⁴⁸ 1976 AIR FORCE PAMPHLET 110-31 ¶2-1g (“An air defense identification zone does not constitute a claim of

sovereignty over airspace above the high seas. Such a zone is merely a reference point for initiation of identification

procedures for aircraft on a course to penetrate national airspace.”).

⁴⁹ See, e.g., John Kerry, Secretary of State, Press Statement (Nov. 23, 2013) (“We don’t support efforts by any State

to apply its ADIZ procedures to foreign aircraft not intending to enter its national airspace. The United States does

not apply its ADIZ procedures to foreign aircraft not intending to enter U.S. national airspace.”); U.S. Response to

Chinese Legal Views, 2001 DIGEST OF UNITED STATES PRACTICE IN INTERNATIONAL LAW 703, 707 (“The U.S. does

not recognize the right of a coastal nation to apply its ADIZ procedures to foreign aircraft not intending to enter

national airspace, and does not apply its ADIZ procedures to foreign aircraft not intending to enter U.S. airspace.”).

⁵⁰ 1976 AIR FORCE PAMPHLET 110-31 ¶2-1g (“State aircraft on a course to penetrate United States airspace may be

requested to identify themselves, and failing voluntary identification may be identified by intercept aircraft or

otherwise as appropriate.”).

⁵¹ Compare § 14.5.2.1 (Failure to Comply by Civil Aircraft).

⁵² Refer to § 13.9.2 (Use of Zones to Warn Vessels or Aircraft - War, Operational, Warning, and Safety Zones);

§ 14.8.3.1 (Protection of Civil Aircraft in Peacetime).

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14.3 AIRCRAFT STATUS

14.3.1 State Versus Civil Aircraft. The 1944 Chicago Convention distinguishes between

State aircraft and civil aircraft.⁵³

Aircraft used in military, customs, and police services are deemed to be State aircraft for

the purposes of the 1944 Chicago Convention.⁵⁴ More generally, State aircraft may be

understood to include other aircraft operated by a government for sovereign, non-commercial

purposes.⁵⁵ In U.S. practice, DoD contract aircraft have not qualified as State aircraft, unless

specifically designated as such by the United States.⁵⁶

The distinction between State aircraft and civil aircraft may be important for a variety of

reasons. For example, the 1944 Chicago Convention generally does not apply to State aircraft.⁵⁷

In addition, enemy State aircraft are subject to seizure as war booty.⁵⁸ As another example,

neutral State aircraft are not subject to visit and search or diversion.⁵⁹ And, although not

⁵³ 1944 CHICAGO CONVENTION art. 3(a) (“This Convention shall be applicable only to civil aircraft, and shall not be

applicable to state aircraft.”). Consider Commission of Jurists to Consider and Report Upon the Revision of the

Rules of Warfare, General Report, Part II: Rules of Aërial Warfare, art. 2, Feb. 19, 1923, reprinted in 32 AJIL

SUPPLEMENT: OFFICIAL DOCUMENTS 12, 12 (1938) (“The following shall be deemed to be public aircraft: (a)

Military aircraft.

(b) Non-military aircraft exclusively employed in the public service. All other aircraft shall be

deemed to be private aircraft.”).

⁵⁴ 1944 CHICAGO CONVENTION art. 3(b) (“Aircraft used in military, customs and police services shall be deemed to

be state aircraft.”).

⁵⁵ DOD DIRECTIVE 4500.54E, DoD Foreign Clearance Program (FCP), Glossary (Dec. 28, 2009) (“state aircraft.

Aircraft, including U.S. military aircraft, operated by a government for sovereign, non-commercial purposes.”).

⁵⁶ See, e.g., Secretary of State Cable 22631, USG Policy Regarding Status of DOD Commercial Contract Aircraft

(Mar. 10, 2010) (The U.S. Government “has consistently taken the position that Department of Defense (DoD)

commercial contract aircraft and other USG contract aircraft are not state aircraft unless the particular aircraft is

specifically designated as such by the USG. The normal practice of the USG is not to designate contract aircraft as

state aircraft.”); 2007 NWP 1-14M ¶2.4.3 (“Auxiliary aircraft are State aircraft, other than military aircraft, that are

owned by or under the exclusive control of the armed forces. Civilian owned and operated aircraft, the full capacity

of which has been contracted by the DOD and used in the military service of the United States, qualify as ‘auxiliary

aircraft’ if they are designated as ‘State aircraft’ by the United States. In those circumstances they too enjoy

sovereign immunity from foreign search and inspection. As a matter of policy, however, the United States normally

does not designate Air Mobility Command-charter aircraft as State aircraft.”); Department of the Army, Office of

the Judge Advocate General, International and Operations Law: Payment of Fees Charged to State Aircraft, 21

THE REPORTER 19, 20 (June 1994) (“The US government consistently has taken the position that Department of

Defense contract aircraft do not qualify as state aircraft unless the particular aircraft is specifically designated as

such by the US government. Although many SOFAs, base rights, and other agreements grant DoD contract aircraft

the same rights of access, exit, and freedom from landing fees and similar charges enjoyed by US military aircraft,

such agreements do not have the effect of declaring DoD contract aircraft to be military aircraft or any form of state

aircraft.”).

⁵⁷ Refer to § 14.1.1.2 (1944 Chicago Convention and Military Aircraft or Other State Aircraft).

⁵⁸ Refer to § 14.5.3 (Capture of Aircraft and Goods on Board Aircraft).

⁵⁹ Refer to § 15.13 (Belligerent Right of Visit and Search of Merchant Vessels and Civil Aircraft); 14.5.2 (Diversion

of Aircraft).

909

necessary for an aircraft to constitute a military objective, the status of an aircraft as State aircraft

may also be an important factor in determining that an aircraft constitutes a military objective.⁶⁰

14.3.2 Nationality of Aircraft. State aircraft possess the nationality of the State that

operates them. Civil aircraft possess the nationality of the State in which they are registered.⁶¹

The nationality of an aircraft may be important in assessing whether it constitutes an

enemy or neutral aircraft.⁶²

14.3.3 Status of Military Aircraft. Military aircraft may be understood as aircraft that are

designated as such by a State that operates them. The United States has not ratified a treaty that

requires certain qualifications before an aircraft may be designated as military aircraft.

In general, military aircraft are operated by commissioned units of the armed forces of a

State, bearing the military markings of that State, and commanded by a member of the armed

forces of that State.

In addition to combat aircraft such as fighters and bombers, other types of aircraft

operated by the armed forces of a State may also be designated as military aircraft, such as

transport, reconnaissance, and meteorological aircraft. Unmanned aircraft, i.e., aircraft that are

remotely piloted or controlled, may also be designated as military aircraft.

14.3.3.1 Military Aircraft - Rights and Liabilities. Of all aircraft, only military

aircraft are entitled to engage in attacks in armed conflict.⁶³ Likewise, during armed conflict,

enemy military aircraft generally constitute military objectives and, thus, may be made the object

of attack, whether in the air or on the ground.⁶⁴ There may be exceptions to the general rule that

enemy military aircraft are liable to being made the object of attack, such as in the case of enemy

military medical aircraft or enemy military aircraft that have surrendered.⁶⁵

⁶⁰ Refer to § 14.8.3 (Attacks Against Civil Aircraft); § 5.7 (Military Objectives).

⁶¹ 1944 CHICAGO CONVENTION art. 17 (“Aircraft have the nationality of the State in which they are registered.”).

⁶² Refer to § 15.14 (Acquisition of Enemy Character by Neutral-Flagged Merchant Vessels and Neutral-Marked

Civil Aircraft).

⁶³ See, e.g., 2013 GERMAN MANUAL ¶1103 (“Only military aircraft are entitled to exercise belligerent rights and use

military force in fighting military objectives of an adversary (14 13, 16 para.1).”); 2006 AUSTRALIAN MANUAL ¶8-

14 (“[O]nly military aircraft can exercise the combat rights of a belligerent. Examples of such rights include

attacking military objectives and overflying enemy territory.”); 2004 UK MANUAL ¶12.34 (“Only military aircraft

may carry out attacks.”); 2001 CANADIAN MANUAL ¶704(3) (“Civil aircraft and state aircraft that are not military

aircraft (for example, police or customs officials) may not engage in hostilities

”); 1976 AIR FORCE PAMPHLET

110-31 ¶2-6d (“Only military aircraft may exercise such rights of belligerents as attacking and destroying military

objectives or transporting troops in the adversary’s national airspace or behind its lines.”). Consider Commission of

Jurists to Consider and Report Upon the Revision of the Rules of Warfare, General Report, Part II: Rules of Aërial

Warfare, art. 16, Feb. 19, 1923, reprinted in 32 AJIL SUPPLEMENT: OFFICIAL DOCUMENTS 12, 19 (1938) (“No

aircraft other than a belligerent military aircraft shall engage in hostilities in any form.”).

⁶⁴ Refer to § 5.7.4.1 (Military Equipment and Bases).

⁶⁵ Refer to § 7.14 (Military Medical Aircraft); § 14.8.2 (Protection of Persons Who Surrender or Who Are Otherwise

Hors De Combat on Board Enemy Aircraft).

910

Belligerent military aircraft generally may not enter neutral airspace.⁶⁶

As State aircraft, military aircraft, like warships, are customarily accorded certain

privileges and immunities by friendly foreign States.⁶⁷

14.3.3.2 Military Aircraft - Markings. Military aircraft are customarily marked to

signify both their nationality and military character.⁶⁸ Markings may help distinguish friend

from foe and help preclude misidentification of aircraft as neutral or as civil.⁶⁹ However,

circumstances may exist where such markings are superfluous.⁷⁰

A single marking may be used to signify both an aircraft’s nationality and its military

character.⁷¹

⁶⁶ Refer to § 15.10.2 (Prohibition on Entry by Belligerent Military Aircraft Into Neutral Airspace).

⁶⁷ DOD DIRECTIVE 4500.54E, DoD Foreign Clearance Program (FCP), ¶4 (Dec. 28, 2009) (“b. Consistent with

U.S. Government policy, DoD aircraft shall not be subject to air navigation, overflight, or similar fees for transit

through the national airspace of another country or through Flight Information Regions in international airspace.

This policy is based upon the unique status of state aircraft, including U.S. military aircraft, in international law as

instruments of a sovereign, and is consistent with international custom and practice. … c. DoD aircraft shall not be

subject to search, seizure, and inspection (including customs, safety, and agriculture inspections) or any other

exercise of jurisdiction by a foreign government over such aircraft, or the personnel, equipment, or cargo on board.

DoD aircraft commanders shall not consent to the exercise of jurisdiction by foreign government authorities over

U.S. military aircraft, except at the direction of the appropriate DoD Component headquarters.”). Consider

Convention Relating to the Regulation of Aerial Navigation, art. 32, Oct. 13, 1919, 11 LNTS 173, 195 (“No military

aircraft of a contracting State shall fly over the territory of another contracting State nor land thereon without special

authorisation. In case of such authorisation the military aircraft shall enjoy, in principle, in the absence of special

stipulation, the privileges which are customarily accorded to foreign ships of war. A military aircraft which is

forced to land or which is requested or summoned to land shall by reason thereof acquire no right to the privileges

referred to in the above paragraph.”); John Cobb Cooper, A Study on the Legal Status of Aircraft, in IVAN A.

VLASIC, EXPLORATIONS IN AEROSPACE LAW 205, 243 (1968) (“It is felt that the rule stated in the Paris Convention

that aircraft engaged in military services should, in the absence of stipulation to the contrary, be given the privileges

of foreign warships when in national port is sound and may be considered as still part of international air law even

though not restated in the Chicago Convention.”).

⁶⁸ Consider Commission of Jurists to Consider and Report Upon the Revision of the Rules of Warfare, General

Report, Part II: Rules of Aërial Warfare, art. 3, Feb. 19, 1923, reprinted in 32 AJIL SUPPLEMENT: OFFICIAL

DOCUMENTS 12, 13 (1938) (“A military aircraft shall bear an external mark indicating its nationality and military

character.”).

⁶⁹ For example, SPAIGHT, AIR POWER AND WAR RIGHTS 82 (“Again and again one finds the fighting airmen of

1914-18 stating in their memoirs or diaries that they have been saved from attacking a friend or have been put on

guard against a foe by seeing the distinguishing marks on the wings of the machines.”).

⁷⁰ 1976 AIR FORCE PAMPHLET 110-31 ¶7-4 (“Military aircraft, as entities of combat in aerial warfare, are also

required to be marked with appropriate signs of their nationality and military character. However, circumstances

may exist where such markings are superfluous and are not required. An example is when no other aircraft except

those belonging to a single state are flown. Such markings serve to distinguish friend from foe and serve to preclude

misidentification as neutral or civilian aircraft. Accordingly, military aircraft may not bear markings of the enemy

or markings of neutral aircraft while engaging in combat. Combatant markings should be prominently affixed to the

exterior aircraft surfaces and be recognizable at a reasonable distance from any direction.”).

⁷¹ For example, 2004 UK MANUAL ¶12.10.4 (“In most air forces, the same marking indicates both nationality and

military character, for example, the Royal Air Force roundel.”).

911

14.3.3.3 Military Aircraft - Command and Crew. Military aircraft are

commanded by members of the armed forces of that State.⁷² The crew, however, may include

civilian members, and such personnel are expressly entitled to POW status under the GPW.⁷³

14.4 STATUS OF AIRCREW ON MILITARY AIRCRAFT

14.4.1 Military Aircrew. Aircrew who are members of the armed forces of a State have

the rights, duties, and liabilities of combatants.⁷⁴ For example, they are entitled to POW status if

they fall into the power of the enemy during international armed conflict, and they have legal

immunity from domestic law for acts done under military authority and in accordance with the

law of war.

14.4.1.1 Wearing of Uniform by Military Aircrew. Military aircrew are required

to distinguish themselves from the civilian population in the same manner as other combatants.⁷⁵

The wearing of flying clothing distinctive to the armed forces satisfies this requirement. In

particular, military aircrew should wear military uniforms (including distinctive flying clothing)

in case they become separated from the aircraft.⁷⁶

14.4.2 Civilian Members of Military Aircrew and Other Persons Authorized to

Accompany the Armed Forces. Civilian members of military aircrew fall into the category of

persons authorized to accompany the armed forces.⁷⁷ Other civilians who are present on military

aircraft or who support the operations of military aircraft may also fall into the category of

persons authorized to accompany the armed forces, provided they have received such

authorization.

As persons authorized to accompany the armed forces, civilian members of military

aircrews are entitled to POW status if they fall into the power of the enemy during international

armed conflict, and they have legal immunity from the enemy’s domestic law for providing

authorized support services to the armed forces. Civilians who work in or on military objectives,

such as military aircraft, assume the risk of harm from attacks against military objectives.⁷⁸

⁷² Consider Commission of Jurists to Consider and Report Upon the Revision of the Rules of Warfare, General

Report, Part II: Rules of Aërial Warfare, art. 14, Feb. 19, 1923, reprinted in 32 AJIL SUPPLEMENT: OFFICIAL

DOCUMENTS 12, 18 (1938) (“A military aircraft shall be under the command of a person duly commissioned or

enlisted in the military service of the state;”).

⁷³ Refer to § 4.15 (Persons Authorized to Accompany the Armed Forces).

⁷⁴ Refer to § 4.5 (Armed Forces of a State); § 4.4 (Rights, Duties, and Liabilities of Combatants).

⁷⁵ Refer to § 5.14.5 (Carrying Arms Openly and Wearing of Distinctive Emblems by the Armed Forces to

Distinguish Themselves From the Civilian Population).

⁷⁶ Consider Commission of Jurists to Consider and Report Upon the Revision of the Rules of Warfare, General

Report, Part II: Rules of Aërial Warfare, art. 15, Feb. 19, 1923, reprinted in 32 AJIL SUPPLEMENT: OFFICIAL

DOCUMENTS 12, 18 (1938) (“Members of the crew of a military aircraft shall wear a fixed distinctive emblem of

such character as to be recognizable at a distance in case they become separated from their aircraft.”).

⁷⁷ Refer to § 4.15 (Persons Authorized to Accompany the Armed Forces).

⁷⁸ Refer to § 5.12.3.2 (Harm to Certain Individuals Who May Be Employed In or On Military Objectives).

912

14.4.3 Downed Aircrew. There are a number of law of war issues related to downed

aircrew.

14.4.3.1 Protection of Aircrew While Parachuting From an Aircraft in Distress.

In general, aircrew parachuting from an aircraft in distress are treated as though they are hors de

combat, i.e., they must not be made the object of attack.⁷⁹ Aircrew parachuting from an aircraft

in distress who engage in hostile acts or attempt to evade capture, either while descending or

after reaching the ground, forfeit any protection from being made the object of attack.⁸⁰

14.4.3.2 Protection of Downed Aircrew at Sea. Downed aircrew at sea are

generally to be regarded as shipwrecked, as the definition of shipwrecked includes forced

landings at sea by or from aircraft.⁸¹ As shipwrecked persons, they must not be made the object

of attack, and there are obligations to search for and collect them.⁸²

14.4.3.3 Rescue of Downed Aircrew. The rescue of downed aircrew to prevent

their capture by the adversary is generally regarded as a combat activity that enemy military

forces may legitimately oppose.⁸³ Medical personnel, ships, or aircraft engaged in the rescue of

downed aircrew must not hamper or interfere with the efforts of opposing military forces to

capture downed aircrew or they will forfeit protection from being made the object of attack as a

result.⁸⁴

The United States has understood the prohibition against the use of riot control agents as

a method of warfare not to prohibit the use of riot control agents to rescue downed aircrew in

certain circumstances.⁸⁵

14.4.3.4 Downed Aircrew - Evasion From, and Capture by, the Enemy. Downed

aircrew may use enemy uniforms to evade capture by the enemy, but, in some cases, such use

may risk liability to treatment as a spy.⁸⁶ Likewise, downed aircrew may use civilian clothes to

evade capture by the enemy.⁸⁷

⁷⁹ Refer to § 5.10.5 (Persons Parachuting From an Aircraft in Distress).

⁸⁰ Refer to § 5.10.5.1 (No Hostile Acts or Attempts to Evade Capture).

⁸¹ Refer to § 7.3.1.2 (Shipwrecked).

⁸² Refer to § 7.3.3 (Meaning of “Respect and Protection” of the Wounded, Sick, and Shipwrecked); § 7.4.1 (GWS-

Sea Obligation Regarding the Search, Collection, and Affirmative Protection of the Wounded, Sick, Shipwrecked,

and Dead).

⁸³ 2004 UK MANUAL ¶12.70.1 (“The use of, for example, military assets to rescue aircrew who have been ‘downed’

on territory under the control of the enemy is a combat activity. It is therefore legitimate for an enemy in such

circumstances to attack the rescuers or by some other means to impede or prevent the rescue activity.”).

⁸⁴ Refer to § 4.9.2.3 (Exclusively Engaged in Humanitarian Duties); § 7.12.2.3 (No Hampering the Movement of

Combatants ); § 7.14.2.2 (Search, Rescue, or Other Recovery Excluded).

⁸⁵ Refer to § 6.16.2 (Prohibition on Use of Riot Control Agents as a Method of Warfare).

⁸⁶ Refer to § 5.23.1.4 (Use of Enemy Uniforms to Evade Capture or Escape).

⁸⁷ Refer to § 5.25.3 (Examples of Other Deceptions That Are Not Prohibited). Compare § 9.25.2.2 (Only

Disciplinary Punishments in Respect of an Act of Escape).

913

If downed aircrew fall into the power of the enemy during international armed conflict,

they are entitled to POW status.⁸⁸ Downed aircrew remain entitled to POW status even if they

unsuccessfully attempt to escape capture by enemy forces or if they attack enemy forces upon

reaching the ground. As POWs, downed aircrew are entitled to protection from violence from

the civilian population and others.⁸⁹

14.4.3.5 Downed Aircrew in Neutral Territory. Military aircrew forced to land in

neutral territory due to navigational failure, combat damage, mechanical failure, or other

emergencies are subject to internment by the neutral State for the duration of the conflict.⁹⁰

14.5 MEASURES SHORT OF ATTACK: INTERCEPTION, DIVERSION, AND CAPTURE

14.5.1 Interception. During armed conflict, a party may choose to intercept an aircraft

through a variety of ways, including closing to visual range or to a distance where the target

aircraft is within the range of weapons systems. Interception of civil aircraft that are not military

objectives should be exercised with due regard for the safety of such aircraft.⁹¹

14.5.1.1 Purposes for Conducting Interception. Interception may have a variety

of purposes, including, for example:

• to assist in the obligation to distinguish between military objectives and civilian objects

and the obligation to protect the civilian population,⁹² such as by

o warning a civil aircraft to refrain from entering an area of active operations; or

o helping identify whether the aircraft constitutes a military objective;

• as part of the belligerent right of visit and search, including the belligerent right to

enforce a blockade,⁹³ such as by

o facilitating identification of an aircraft (e.g., enemy or neutral);

o forcing an aircraft to divert and land at a specific airfield for search or capture; or

• to be in a position to attack the aircraft.

14.5.1.2 Airspace Where Interception May Be Conducted. As a general rule,

belligerent military aircraft may not intercept aircraft in neutral airspace.⁹⁴

⁸⁸ Refer to § 9.3 (POW Status).

⁸⁹ Refer to § 9.5.2.2 (Protection Against Violence by the Civilian Population or Others).

⁹⁰ Refer to § 15.16 (Belligerent Forces Taking Refuge in Neutral Territory).

⁹¹ Refer to § 14.1.1.4 (Due Regard for the Safety of Navigation of Civil Aircraft).

⁹² Refer to § 2.5 (Distinction).

⁹³ Refer to § 15.13 (Belligerent Right of Visit and Search of Merchant Vessels and Civil Aircraft).

⁹⁴ Refer to § 15.10 (Neutral Airspace).

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In addition, interception may not be conducted during passage through neutral

international straits or neutral archipelagic sea lanes.⁹⁵

14.5.2 Diversion of Aircraft. Diversion and search of civil aircraft may be conducted

outside neutral airspace as part of the belligerent right of visit and search (e.g., to help determine

whether aircraft are liable to capture for carriage of contraband or for breach of blockade).⁹⁶

Interference with civil aircraft of neutral States must be justified by military necessity.

If, upon interception outside of neutral airspace, reasonable grounds exist for suspecting

that the intercepted civil aircraft, its cargo, or its personnel are liable to capture,⁹⁷ then it may be

directed to proceed to a belligerent airfield that is both reasonably accessible and suitable for the

type of aircraft involved for visit and search.⁹⁸ Should such an airfield not be available, the

intercepted civil aircraft may be diverted from its declared destination.⁹⁹

Certain aircraft are exempt from the belligerent right to divert aircraft for purposes of

visit and search:

(1) neutral military aircraft; and (2) neutral civil aircraft accompanied by

neutral military aircraft of the same nationality.¹⁰⁰

14.5.2.1 Failure to Comply by Civil Aircraft. An enemy civil aircraft that

persistently fails to comply with military instructions becomes a military objective subject to

attack.¹⁰¹

Failure to comply with military instructions from intercepting aircraft does not in itself

render a neutral or non-belligerent civil aircraft a military objective. However, it may provide

strong evidence that the civil aircraft is in fact being used for a military or hostile purpose.

14.5.3 Capture of Aircraft and Goods on Board Aircraft. Enemy civil aircraft and goods

on board such aircraft may be captured outside neutral airspace.¹⁰²

⁹⁵ Refer to § 15.8 (Passage of Belligerent Vessels and Aircraft Through International Straits and Archipelagic Sea

Lanes).

⁹⁶ Refer to § 15.13.4.3 (Visit and Search of Civil Aircraft by Military Aircraft).

⁹⁷ Refer to § 15.15.1 (Grounds for the Capture of Neutral Vessels and Aircraft).

⁹⁸ Consider Commission of Jurists to Consider and Report Upon the Revision of the Rules of Warfare, General

Report, Part II: Rules of Aërial Warfare, art. 50, Feb. 19, 1923, reprinted in 32 AJIL SUPPLEMENT: OFFICIAL

DOCUMENTS 12, 44 (1938) (“Belligerent military aircraft have the right to order public non-military and private

aircraft to alight in or proceed for visit and search to a suitable locality reasonably accessible. Refusal, after

warning, to obey such orders to alight or to proceed to such a locality for examination exposes an aircraft to the risk

of being fired upon.”).

⁹⁹ 2007 NWP 1-14M ¶7.6.3 (“If, upon interception outside of neutral airspace, reasonable grounds exist for

suspecting that the intercepted civilian aircraft is carrying contraband cargo or that, despite its neutral markings, it is,

in fact, enemy, it may be directed to proceed for visit and search to a belligerent airfield that is both reasonably

accessible and suitable for the type of aircraft involved. Should such an airfield not be available, the intercepted

civilian aircraft may be diverted from its declared destination.”).

¹⁰⁰ Refer to § 15.13.2 (Types of Neutral Vessels and Aircraft That Are Exempt From Visit and Search).

¹⁰¹ Refer to § 14.8.3.2 (Forfeiture of Protection From Being Made the Object of Attack During Armed Conflict).

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Any enemy State aircraft (including military, law enforcement, and customs aircraft), as

public movable property, is subject to capture as war booty with ownership passing immediately

to the captor government.¹⁰³ Similarly, prize procedure is not used for captured enemy

warships.¹⁰⁴

Neutral civil aircraft engaged in certain activity in violation of their neutral status are

liable to capture.¹⁰⁵ Even if not liable to capture, neutral civil aircraft are subject to visit and

search.¹⁰⁶

14.6 BELLIGERENT CONTROL OF AVIATION IN THE IMMEDIATE VICINITY OF HOSTILITIES

Belligerents may prohibit or establish special restrictions upon flight activities in the

immediate vicinity of hostilities to prevent such activities from jeopardizing military operations.

In some cases, this right may be distinct from a belligerent State’s right to establish airspace

zones during armed conflict.¹⁰⁷

As with the belligerent right to control the immediate area of naval operations, this right

is based on a belligerent State’s right to ensure the security of its forces and its right to conduct

hostilities without interference from neutrals.¹⁰⁸ However, belligerent control of aviation in the

immediate vicinity of hostilities may be applicable in the national airspace of belligerents.¹⁰⁹

14.7 AIRSPACE ZONES

During armed conflict, States may establish airspace zones and associated procedures

intended to prohibit aircraft from entering or flying in designated areas, including areas in

¹⁰² Consider Commission of Jurists to Consider and Report Upon the Revision of the Rules of Warfare, General

Report, Part II: Rules of Aërial Warfare, art. 49, Feb. 19, 1923, reprinted in 32 AJIL SUPPLEMENT: OFFICIAL

DOCUMENTS 12, 40 (1938) (“Private aircraft are liable to visit and search and to capture by belligerent military

aircraft.”); Commission of Jurists to Consider and Report Upon the Revision of the Rules of Warfare, General

Report, Part II: Rules of Aërial Warfare, art. 52, Feb. 19, 1923, reprinted in 32 AJIL SUPPLEMENT: OFFICIAL

DOCUMENTS 12, 45 (1938) (“Enemy private aircraft are liable to capture in all circumstances.”).

¹⁰³ Refer to § 5.17.3 (Enemy Movable Property on the Battlefield (War Booty)). Consider Commission of Jurists to

Consider and Report Upon the Revision of the Rules of Warfare, General Report, Part II: Rules of Aërial Warfare,

art. 32, Feb. 19, 1923, reprinted in 32 AJIL SUPPLEMENT: OFFICIAL DOCUMENTS 12, 30 (1938) (“Enemy public

aircraft, other than those treated on the same footing as private aircraft, shall be subject to confiscation without prize

proceedings.”); Program on Humanitarian Policy and Conflict Research at Harvard University, Commentary on the

HPCR Manual on International Law Applicable to Air and Missile Warfare, 275 (U.I.136(a)) (2010) (“Enemy

military, law-enforcement and customs aircraft are booty of war. Prize procedures do not apply to captured enemy

military aircraft and other State aircraft, inasmuch as their ownership immediately passes to the captor government

by virtue of capture.”).

¹⁰⁴ Refer to § 13.4.3 (Captured Enemy Warships - No Prize Procedure).

¹⁰⁵ Refer to § 15.15.1 (Grounds for the Capture of Neutral Vessels and Aircraft).

¹⁰⁶ Refer to § 15.13 (Belligerent Right of Visit and Search of Merchant Vessels and Civil Aircraft).

¹⁰⁷ Refer to § 14.7 (Airspace Zones).

¹⁰⁸ Refer to § 13.8 (Belligerent Control of the Immediate Area of Naval Operations).

¹⁰⁹ Refer to § 14.2.1.1 (National Airspace).

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international airspace. Such zones may be established for a variety of purposes, including to

decrease the risk of inadvertent attack of civil or neutral aircraft, to control the scope of the

conflict, or to enhance the predictability and effectiveness of ongoing operations.

The legal rules that apply to the establishment and enforcement of a zone are discussed in

connection with the establishment and enforcement of maritime zones.¹¹⁰

In some cases, such as with Air Defense Identification Zones, the zone may be

established during peacetime.¹¹¹

14.8 ATTACKS AGAINST MILITARY OBJECTIVES IN THE AIR

The general rules on conducting attacks also apply to attacks against military objectives

in the air.¹¹² In general, enemy military aircraft may be made the object of attack.

14.8.1 Medical Aircraft. Specific rules found in the 1949 Geneva Conventions address

the protection of aircraft that are engaged exclusively in specified medical functions.¹¹³

14.8.2 Protection of Persons Who Surrender or Who Are Otherwise Hors De Combat on

Board Enemy Aircraft. The general rules on the protection of persons who are hors de combat

(such as those who have been incapacitated and those who have effectively surrendered) also

apply to persons on board enemy aircraft.¹¹⁴

Although the capture of enemy military aircraft and aircrew may be of significant

intelligence value, there are often significant practical obstacles to identifying when persons on

board an aircraft are hors de combat and to accepting their surrender. Despite these practical

difficulties, if surrender is offered in good faith and circumstances do not preclude enforcement,

then surrender must be respected.¹¹⁵ Persons who are conducting attacks against enemy military

aircraft must assess in good faith whether surrender is offered in good faith and can feasibly be

accepted based on the information that is available to them at the time.¹¹⁶

14.8.2.1 Difficulty in Identifying Persons on Board Aircraft as Hors De Combat.

As a practical matter, it may be quite difficult to establish that persons on board enemy aircraft

are hors de combat and may no longer be made the object of attack.

First, it is very difficult, if not impossible, to assess whether the enemy aircraft has

actually been disabled and does not pose any threat. For example, aircraft may feign symptoms

¹¹⁰ Refer to § 13.9 (Maritime and Airspace Zones: Exclusion, War, Operational, Warning, and Safety).

¹¹¹ Refer to § 14.2.4 (Air Defense Identification Zone (ADIZ)).

¹¹² Refer to § 5.5.2 (Overview of Rules in Conducting Attacks).

¹¹³ Refer to § 7.14 (Military Medical Aircraft); § 7.19 (Civilian Medical Aircraft).

¹¹⁴ Refer to § 5.10 (Persons Placed Hors de Combat).

¹¹⁵ 1976 AIR FORCE PAMPHLET 110-31 ¶4-2d (“If surrender is offered in good faith so that circumstances do not

preclude enforcement, then surrender must be respected.”).

¹¹⁶ Refer to § 5.4.2 (Decisions Must Be Made in Good Faith and Based on Information Available at the Time).

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of distress to evade enemy attacks.¹¹⁷ Moreover, even if an aircraft has been disabled in some

respects, the aircraft may not have lost its means of combat, and weapons on board the aircraft

may still pose a threat.

As a practical matter, it may also be difficult for the pilot of an attacking aircraft to know

when an adversary is attempting to surrender or has surrendered. Broadcasting on the

international GUARD frequency (aircraft emergency frequency), rocking the aircraft’s wings,

lowering the landing gear, and other signals (such as the flashing of navigational lights) are

sometimes cited as indications of a pilot or aircrew’s desire to surrender, but they are not

recognized in law as signals of surrender. Consequently, absent an explicit message of offering

surrender, an intention to surrender cannot be presumed from the conduct of the aircraft.

14.8.2.2 Feasibility of Accepting Surrender by Enemy Aircraft. In many

circumstances, it may not be feasible to accept the surrender of enemy aircraft.¹¹⁸ For example,

it may not be possible to enforce surrender when the engagement takes place over enemy

territory.¹¹⁹

14.8.3 Attacks Against Civil Aircraft. During armed conflict, civil aircraft are generally

considered civilian objects, but may be made the object of attack, outside neutral territory, if they

constitute a military objective.

14.8.3.1 Protection of Civil Aircraft in Peacetime. Under customary international

law applicable during peacetime, States have an obligation to refrain from resorting to the use of

weapons against civil aircraft in flight.¹²⁰ However, this obligation does not modify in any way

¹¹⁷ Refer to § 5.25.3 (Examples of Other Deceptions That Are Not Prohibited).

¹¹⁸ 1976 AIR FORCE PAMPHLET 110-31 ¶4-2d (“Surrenders in air combat are generally not offered. If surrender is

offered, usually no way exists to enforce the surrender.”).

¹¹⁹ 2004 UK MANUAL ¶12.64 (“Although it is forbidden to kill or wound an enemy who, having laid down his arms,

or having no longer means of defence, has surrendered at discretion in air-to-air combat, surrender is usually

impracticable and occurs very infrequently.”); 2004 UK MANUAL ¶12.64.1 (“In the special circumstances of air-to-

air combat the continuation of an attack after an indication by the opponent of a wish to surrender is not inconsistent

with the rule in paragraph 12.64, as the enemy pilot who remains in his aircraft cannot be said to have ‘laid down his

arms’ or to have ‘no longer a means of defence’. However, if the surrender is offered in good faith and in

circumstances that do not prevent enforcement, for example, when the engagement has not taken place over enemy

territory, it must be respected and accepted.”).

¹²⁰ See, e.g., Walter Dellinger, Assistant Attorney General, United States Assistance to Countries that Shoot Down

Civil Aircraft Involved in Drug Trafficking, Jul. 14, 1994, 18 OPINIONS OF THE OFFICE OF LEGAL COUNSEL 148, 149-

50 (“[T]he United States argued that the Soviet Union had violated both Article 3(d) and customary international

legal norms in shooting down KAL 007. … We understand that the United States has not yet ratified Article 3 bis.

There is, however, support for the view that the principle it announced is declaratory of customary international

law.”); U.N. SECURITY COUNCIL RESOLUTION 1067, U.N. Doc. S/RES/1067 (1996) (“6. Condemns the use of

weapons against civil aircraft in flight as being incompatible with elementary considerations of humanity, the rules

of customary international law as codified in article 3 bis of the Chicago Convention, … .”). Consider Protocol

Relating to an Amendment to the Convention on International Civil Aviation (Article 3 bis), May 10, 1984, 2122

UNTS 346-47 (“The contracting States recognize that every State must refrain from resorting to the use of weapons

against civil aircraft in flight and that, in case of interception, the lives of persons on board and the safety of aircraft

must not be endangered. This provision shall not be interpreted as modifying in any way the rights and obligations

of States set forth in the Charter of the United Nations.”).

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the rights and obligations of States set forth in the Charter of the United Nations.¹²¹ Thus, a

State’s use of force against civil aircraft in the exercise of the inherent right of self-defense

would be permitted.

14.8.3.2 Forfeiture of Protection From Being Made the Object of Attack During

Armed Conflict. Civil aircraft may be made the object of attack, outside neutral territory, if the

aircraft constitutes a military objective.¹²²

In particular, civil aircraft forfeit any protection from being made the object of attack if

they acquire the character of enemy military aircraft by:

• taking a direct part in the hostilities on the side of the enemy; or

• acting in any capacity as a naval or military auxiliary to the enemy’s armed forces.¹²³

In addition, enemy civil aircraft forfeit protection from being made the object of

attack:¹²⁴

• when persistently refusing to comply with directions from intercepting aircraft;¹²⁵

• when flying under convoy of enemy warships or military aircraft;

• when armed with systems or weapons beyond that required for self-defense against

terrorism, piracy, or like threats;

• when incorporated into or assisting the enemy’s military intelligence system;¹²⁶ or

¹²¹ Consider Protocol Relating to an Amendment to the Convention on International Civil Aviation (Article 3 bis),

May 10, 1984, 2122 UNTS 346-47 (“The contracting States recognize that every State must refrain from resorting to

the use of weapons against civil aircraft in flight and that, in case of interception, the lives of persons on board and

the safety of aircraft must not be endangered. This provision shall not be interpreted as modifying in any way the

rights and obligations of States set forth in the Charter of the United Nations.”) (emphasis added). Compare

§ 13.1.1 (The Law of the Sea During Armed Conflict).

¹²² Refer to § 5.7 (Military Objectives).

¹²³ Refer to § 15.14.2.1 (Acquiring the Character of an Enemy Warship or Military Aircraft).

¹²⁴ 2007 NWP 1-14M ¶8.8 (“Enemy merchant vessels and civil aircraft may be attacked and destroyed by military

aircraft only under the following circumstances: 1. When persistently refusing to comply with directions from the

intercepting aircraft 2. When sailing under convoy of enemy warships or military aircraft 3. When armed with

systems or weapons beyond that required for self-defense against terrorism, piracy, or like threats 4. When

incorporated into or assisting in any way the enemy’s military intelligence system 5. When acting in any capacity as

a naval or military auxiliary to an enemy’s armed forces 6. When otherwise integrated into the enemy’s war-fighting

or war-sustaining effort.”); 1989 NWP 9 ¶8.4 (“Enemy merchant vessels and civil aircraft may be attacked and

destroyed by military aircraft only under the following circumstances: 1. When refusing to comply with directions

from the intercepting aircraft 2. When assisting in any way the enemy’s military intelligence system or acting in any

capacity as auxiliaries to the enemy’s armed forces 3. When sailing under convoy of enemy warships, escorted by

enemy military aircraft, or armed 4. When otherwise integrated into the enemy’s war-fighting or war-sustaining

effort.”).

¹²⁵ Refer to § 14.5.2.1 (Failure to Comply by Civil Aircraft).

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• when otherwise integrated into the enemy’s war-fighting or war-sustaining effort.

14.8.3.3 Attack of Civilian Passenger Aircraft. If a civilian passenger aircraft

constitutes a military objective and thus is liable to attack, any attack must comply with other

applicable rules related to attacks.¹²⁷

In particular, attacks against civilian passenger aircraft engaged in passenger service must

comply with the requirement that the expected loss of life or injury to civilians, and damage to

civilian objects incidental to the attack, must not be excessive in relation to the concrete and

direct military advantage expected to be gained.¹²⁸

14.9 AIR ATTACKS AGAINST MILITARY OBJECTIVES ON THE GROUND

The general rules on conducting attacks also apply to air attacks against military

objectives on the ground.¹²⁹

14.9.1 Prohibition Against Bombardment of Undefended Cities, Towns, and Villages.

The aerial bombardment of towns, villages, dwellings, or buildings that are undefended is

prohibited.¹³⁰ The phrase “by whatever means” was inserted in the Hague IV Regulations to

clarify that bombing attacks by air were included in this rule.¹³¹

An “undefended” city, town, or village in this sense is a term of art. For example, a city

may only be declared “undefended” if it is open for immediate physical occupation by opposing

military ground forces.¹³²

14.9.2 Selection of Weapons in Conducting Attacks From the Air Against Ground

Military Objectives. It may be the case that commanders will have a variety of weapons with

which to conduct a potential aerial bombardment.

Certain weapons are prohibited per se, and it is specifically provided that feasible

precautions be taken in connection with certain weapons.¹³³ It must be emphasized, however,

that the selection of the appropriate weapon for conducting an aerial bombardment remains

primarily a military judgment rather than a legal one. In particular, there is no law of war

¹²⁶ Consider Commission of Jurists to Consider and Report Upon the Revision of the Rules of Warfare, General

Report, Part I: Rules for the Control of Radio in Time of War, art. 6, Feb. 19, 1923, reprinted in 32 AJIL

SUPPLEMENT: OFFICIAL DOCUMENTS 2, 7-8 (1938) (“1. The transmission by radio by a vessel or an aircraft, whether

enemy or neutral, when on or over the high seas of military intelligence for the immediate use of a belligerent is to

be deemed a hostile act and will render the vessel or aircraft liable to be fired upon.”).

¹²⁷ Refer to § 5.5 (Rules on Conducting Assaults, Bombardments, and Other Attacks).

¹²⁸ Refer to § 5.12 (Proportionality in Conducting Attacks).

¹²⁹ Refer to § 5.5.2 (Overview of Rules in Conducting Attacks).

¹³⁰ Refer to § 5.15 (Undefended Cities, Towns, and Villages).

¹³¹ Refer to § 5.15.2 (“By Whatever Means”).

¹³² Refer to § 5.15.3 (Declaration of a City as “Undefended”).

¹³³ Refer to § 6.4 (Prohibited Weapons); § 5.3.3.3 (Requirements to Take Precautions Regarding Specific Weapons).

920

requirement to use precision-guided weapons when non-precision-guided weapons may be used

in compliance with the law of war.¹³⁴

Commanders have a general obligation to take feasible precautions in conducting attacks

in order to reduce the risk of harm to the civilian population.¹³⁵ The selection of weapons may

be among the available precautions that a commander could take in order to reduce the risk of

harm to the civilian population.

14.9.3 Protection of Enemy Ground Forces Who Are Hors de Combat. When aircrew or

aircraft operators assess that an enemy combatant has been placed hors de combat, they must

refrain from making such persons the object of attack.¹³⁶

In order to place a person hors de combat, the person’s surrender must be (1) genuine; (2)

clear and unconditional; and (3) under circumstances where it is feasible for the opposing party

to accept the surrender.¹³⁷

In many cases, it would not be feasible for a party that is conducting air operations to

accept the surrender of an enemy person. In some cases, however, it may be appropriate, in

order to facilitate such surrender, to communicate steps for enemy units to take to communicate

clearly their intention to surrender.¹³⁸

14.9.3.1 Difficulty in Identifying Persons Placed Hors De Combat. The

identification by aircraft of an enemy combatant on the ground placed hors de combat may pose

a particular challenge. It may be difficult for aircrew or aircraft operators to determine whether

an enemy combatant is dead, injured, merely taking cover, or feigning injury or surrender to

avoid attack.¹³⁹ On the other hand, it may be difficult for enemy combatants on the ground to

¹³⁴ Refer to § 5.11.3 (Selecting Weapons (Weaponeering)).

¹³⁵ Refer to § 5.11 (Feasible Precautions in Conducting Attacks to Reduce the Risk of Harm to Protected Persons and

Objects).

¹³⁶ Refer to § 5.10 (Persons Placed Hors de Combat).

¹³⁷ Refer to § 5.10.3 (Persons Who Have Surrendered).

¹³⁸ Captain M. Scott Holcomb, View from the Legal Frontlines, 4 CHICAGO JOURNAL OF INTERNATIONAL LAW 561,

566-67 (2003) (“In August 2002, I met with Commander Kenneth O’Rourke, the Chief of Operational Law at

CENTCOM, and Lieutenant Commander Gregory Bart, the Special Operations Command Central (‘SOCCENT’)

Staff Judge Advocate to develop legally supportable concepts that would achieve the commander’s intent to either

have Iraqi units assist Coalition forces or indicate a desire not to fight and remain in place, preferably in their

barracks. … Consequently, we sketched an outline for an operational plan to encourage units to capitulate.

Coalition forces would contact Iraqi units through various means including leaflet drops, radio broadcasts, and

surrogates who would inform the commander of his opportunity to surrender with honor and preserve his unit. Iraqi

units would receive these messages shortly before the air campaign started to give them time to perform the required

actions, but not so much time that they would be subject to regime reprisals. If the unit performed certain

observable actions, such as forming their vehicles in a square, then Special Forces would approach the unit and offer

articles of capitulation for the surrender of the unit.”).

¹³⁹ See SPAIGHT, AIR POWER AND WAR RIGHTS 132 (“In the second world war also there were one or two instances

in which ground forces showed the white flag to aircraft. … Other circumstances are conceivable in which there

could be no assurance that the display of a white flag was not a ruse to enable the enemy troops to escape after the

immediate danger was past. In such circumstances it could he [sic] held that the airmen were under no obligation to

discontinue their attack.”).

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communicate clearly to aircraft that they wish genuinely to surrender unconditionally or that they

have been incapacitated.

Aircrew or aircraft operators must assess in good faith whether persons have been placed

hors de combat based on the information that is available to them at the time.¹⁴⁰

14.9.3.2 Feasibility of Air Units to Accept the Surrender of Ground Forces. For a

communication of surrender to place a person hors de combat, the person must make the

surrender under circumstances where it is feasible for the opposing party to accept the

surrender.¹⁴¹ For example, it must be possible for the opposing party to take that person into

custody.¹⁴²

In many cases, it would not be feasible for the aircraft to land and take the person into

custody or for nearby ground forces to take the person into custody.¹⁴³

14.10 INTERNATIONAL LAW AND WARFARE IN OUTER SPACE

14.10.1 Classification of Outer Space. Outer space is governed by a separate legal

regime than that for airspace.¹⁴⁴

¹⁴⁰ Refer to § 5.4.2 (Decisions Must Be Made in Good Faith and Based on Information Available at the Time).

¹⁴¹ Refer to § 5.10.3.3 (Under Circumstances in Which It Is Feasible to Accept).

¹⁴² For example, FINAL REPORT ON THE PERSIAN GULF WAR 381 (“During this attack, the two companies of 3/1

Attack Helicopter Battalion encountered minimal resistance in the form of T-55 tanks and BMPs, which they

destroyed. The surprising aspect of this operation was that it was the first of many instances where hundreds of Iraqi

soldiers ran out of their bunkers and attempted to surrender after seeing Army helicopters in their midst. Without

the means to hold them, the aeroscout pilots played ‘cowboys’ to the ‘herd’ of Iraqi soldiers, hovering them into a

tight circle until the lead ground elements of the Division's 1st Brigade arrived and secured them.”); FINAL REPORT

ON THE PERSIAN GULF WAR 212 (“In addition to direct support of NGFS missions, UAVs also were used to gather

intelligence on Faylaka Island when national sensors were not available and weather prevented aircraft

reconnaissance. Over Faylaka Island, USS Wisconsin’s UAV recorded hundreds of Iraqi soldiers waving white flags

- the first-ever surrender of enemy troops to an unmanned aircraft. After the cease-fire, UAVs monitored the

coastline and outlying islands in reconnaissance support of occupying Coalition forces. Because UAVs were under

direct tactical control of combat forces, they could respond quickly in dynamic situations. On one occasion, USS

Wisconsin’s UAV located two Iraqi patrol boats, which were sunk by aircraft directed to investigate.”).

¹⁴³ For example, 101st Airborne ROE Card, Iraq (2003), reprinted in CENTER FOR LAW AND MILITARY OPERATIONS,

THE JUDGE ADVOCATE GENERAL’S LEGAL CENTER & SCHOOL, U.S. ARMY, I LEGAL LESSONS LEARNED FROM

AFGHANISTAN AND IRAQ: MAJOR COMBAT OPERATIONS (11 SEPTEMBER 2001 - 1 MAY 2003) 315, 316 (2004) (“3.

Facts: An armed soldier sees you and throws his hands up to surrender. Response: Take the soldier prisoner, and

treat as an EPW. (Note: aircraft are not in the position to accept surrender, in the foregoing scenario, a 101st ABD

aircraft could fire upon the enemy soldier).”); SPAIGHT, AIR POWER AND WAR RIGHTS 131-32 (“Usually it is

impossible for attacking airmen to take ground troops prisoners, and such a situation as that described by Lieut.-Col.

Tennant as arising in Iraq in February, 1917, is probably more typical and normal than the cases quoted above.

Lieut.-Col. Tennant describes how in the Turkish retreat towards Azizieh, after the forcing by General Maude’s

army of the Shumran Bend in the Tigris on 23 February, 1917, ‘many of the waggons had hoisted the white flag,’

while some of the flying Turks ‘waved in token of surrender,’ when the British aeroplanes attacked them with

machine-guns. ‘Flying along about 10 feet from the road I mowed down seven with one burst of machine-gun fire.’

In such circumstances it is impossible to recognise the white flag. To try to do so would be to sacrifice the

advantage of the destruction of a routed and demoralised foe.”).

¹⁴⁴ Refer to § 14.2.2 (Vertical Boundary Between Airspace and Outer Space).

922

Outer space may be viewed as analogous to the high seas in certain respects.¹⁴⁵ For

example, no State may claim sovereignty over outer space.¹⁴⁶ In addition, the space systems of

all nations have rights of passage through space without interference.¹⁴⁷

14.10.2 Application of International Law to Activities in Space.

14.10.2.1 Treaties Specifically Addressing Space Activities. The United States is

a Party to certain treaties that address space activities. The Treaty on Principles Governing the

Activities of States in the Exploration and Use of Outer Space, including the Moon and Other

Celestial Bodies (Outer Space Treaty), imposes restrictions on certain military operations in

outer space (i.e., it does not exempt military spacecraft or military space activities from its

purview).¹⁴⁸ The Outer Space Treaty provides for State responsibility for the activities of non-

governmental entities in outer space, including the moon and other celestial bodies.¹⁴⁹

Other treaties that specifically address space activities include:

• Agreement on the Rescue of Astronauts, the Return of Astronauts, and the Return of

Objects Launched into Outer Space;¹⁵⁰

• Convention on International Liability for Damage Caused by Space Objects;¹⁵¹ and

• Convention on Registration of Objects Launched into Outer Space.¹⁵²

¹⁴⁵ Arthur J. Goldberg, U.S. Ambassador to the United Nations, Treaty on Outer Space: Hearings Before the

Committee on Foreign Relations, U.S. Senate, 90th Congress, First Session, 63 (Mar. 13, 1967) (“This is an attempt,

once we leave airspace, and get to outer space, however you define the limits, this is an attempt to create in outer

space the closest analogy and that is the high seas.”).

¹⁴⁶ OUTER SPACE TREATY art. II (“Outer space, including the moon and other celestial bodies, is not subject to

national appropriation by claim of sovereignty, by means of use or occupation, or by any other means.”).

¹⁴⁷ See, e.g., OUTER SPACE TREATY art. I (“Outer space, including the moon and other celestial bodies, shall be free

for exploration and use by all States without discrimination of any kind, on a basis of equality and in accordance

with international law, and there shall be free access to all areas of celestial bodies.”); National Space Policy of the

United States of America, 3 (Jun. 28, 2010) (“The United States considers the space systems of all nations to have

the rights of passage through, and conduct of operations in, space without interference. Purposeful interference with

space systems, including supporting infrastructure, will be considered an infringement of a nation’s rights.”);

Presidential Directive/NSC-37, National Space Policy, ¶1.d (May 11, 1978) (“The space systems of any nation are

national property and have the right of passage through and operations in space without interference. Purposeful

interference with operational space systems shall be viewed as an infringement upon sovereign rights.”).

¹⁴⁸ Refer to § 14.10.3 (Outer Space Treaty Restrictions on Military Activities).

¹⁴⁹ OUTER SPACE TREATY art. VI (“States Parties to the Treaty shall bear international responsibility for national

activities in outer space, including the moon and other celestial bodies, whether such activities are carried on by

governmental agencies or by non-governmental entities, and for assuring that national activities are carried out in

conformity with the provisions set forth in the present Treaty. The activities of non-governmental entities in outer

space, including the moon and other celestial bodies, shall require authorization and continuing supervision by the

appropriate State Party to the Treaty.”).

¹⁵⁰ Agreement on the Rescue of Astronauts, the Return of Astronauts, and the Return of Objects Launched into

Outer Space, Apr. 22, 1968, 672 UNTS 119.

¹⁵¹ Convention on International Liability for Damage Caused by Space Objects, Mar. 29, 1972, 961 UNTS 187.

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Certain provisions of these treaties may not be applicable as between belligerents during

international armed conflict.¹⁵³

14.10.2.2 Application of General International Law to Activities and Use of Outer

Space. The Outer Space Treaty reaffirms the duty of States Parties to comply with existing

international law in carrying out activities in outer space. Article III of the Outer Space Treaty

provides that “States Parties to the Treaty shall carry on activities in the exploration and use of

outer space, including the moon and other celestial bodies, in accordance with international law,

including the Charter of the United Nations, in the interest of maintaining international peace and

security and promoting international cooperation and understanding.”¹⁵⁴

Although existing international law, such as the Charter of the United Nations, generally

applies to States Parties’ activities in outer space, international law that prescribes certain

conditions for national claims of sovereignty does not apply to outer space because outer space is

not subject to national appropriation.¹⁵⁵

Certain treaties apply only in certain geographical locations (such as a State’s own

territory), and thus might not create obligations applicable to a State’s activities in outer space.

However, law of war treaties and the customary law of war are understood to regulate the

conduct of hostilities, regardless of where they are conducted, which would include the conduct

of hostilities in outer space. In this way, the application of the law of war to activities in outer

¹⁵² Convention on Registration of Objects Launched into Outer Space, Nov. 12, 1974, 1023 UNTS 15.

¹⁵³ Department of Defense, Office of the General Counsel, An Assessment of International Legal Issues in

Information Operations (2nd ed., Nov. 1999), reprinted in 76 U.S. NAVAL WAR COLLEGE INTERNATIONAL LAW

STUDIES 459, 494 (2002) (“During an international armed conflict between the two nations concerned, however, the

law of armed conflict would apply unless it was trumped by the principle of noninterference with space systems.

Resolution of this issue depends largely on whether the four space treaties will be considered to apply during an

armed conflict. None of them has any specific provision that indicates whether the parties intended that the

agreement apply in wartime. There appears to be a strong argument that the principle of noninterference established

by these agreements is inconsistent with a state of hostilities, at least where the systems concerned are of such high

military value that there is a strong military imperative for the adversary to be free to interfere with them, even to the

extent of destroying the satellites in the system. As indicated in the discussion of treaty law in the introduction to

this paper, the outcome of this debate may depend on the circumstances in which it first arises in practice.”).

¹⁵⁴ OUTER SPACE TREATY art. III. See also Staff Report prepared for the use of the Committee on Aeronautical and

Space Sciences, United States Senate, Treaty on Principles Governing the Activities of States in the Exploration and

Use of Outer Space, Including the Moon and Other Celestial Bodies: Analysis and Background Data, 24 (Mar.

1967) (“This article makes clear that those nations which ratify the treaty will observe international law—and this

includes the Charter of the United Nations—in order to promote international cooperation and peace. Thus that

body of law, which has developed on the Earth in order to bring about harmonious relations between nations and

settle disputes without resort to violence, would become applicable to outer space, the Moon, and other celestial

bodies.”).

¹⁵⁵ Staff Report prepared for the use of the Committee on Aeronautical and Space Sciences, United States Senate,

Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the

Moon and Other Celestial Bodies: Analysis and Background Data, 24 (Mar. 1967) (“An exception would be

international law which provides certain conditions for national claims of sovereignty, this exception having been

set forth in Article II.”); OUTER SPACE TREATY art. II (“Outer space, including the moon and other celestial bodies,

is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other

means.”).

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space is the same as its application to activities in other environments, such as the land, sea, air,

or cyber domains.

14.10.3 Outer Space Treaty Restrictions on Military Activities. The Outer Space Treaty

imposes restrictions on certain military operations in outer space.

Other treaties may also impose restrictions on military activities in outer space. For

example, the Treaty Banning Nuclear Testing in the Atmosphere, Oceans, and Outer Space

(Limited Test Ban Treaty) prohibits nuclear weapon test explosions in outer space.¹⁵⁶

14.10.3.1 Restriction on Nuclear Weapons and Other Kinds of Weapons of Mass

Destruction in Outer Space. Article IV of the Outer Space Treaty provides that “States Parties to

the Treaty undertake not to place in orbit around the Earth any objects carrying nuclear weapons

or any other kinds of weapons of mass destruction, install such weapons on celestial bodies, or

station such weapons in outer space in any other manner.”¹⁵⁷

The prohibition on placing weapons of mass destruction “in orbit around the earth” refers

only to their placement in full orbit around the Earth; thus, the Outer Space Treaty does not ban

the use of nuclear or other weapons of mass destruction that go into a fractional orbit or engage

in suborbital flight.¹⁵⁸ For example, intercontinental ballistic missiles (ICBMs) will travel a

portion of their trajectory in outer space; but because ICBMs would enter outer space only

temporarily, their entry into outer space with nuclear warheads would not violate this

prohibition.¹⁵⁹ By contrast, some arms control treaties have prohibited the production, testing, or

deployment of systems, including missiles, that place nuclear weapons or other weapons of mass

destruction into either full earth orbit or a fraction of an earth orbit.¹⁶⁰

¹⁵⁶ Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space and Under Water, art. 1, Aug. 5, 1963,

480 UNTS 43, 45 (“Each of the Parties to this Treaty undertakes to prohibit, to prevent, and not to carry out any

nuclear weapon test explosion, or any other nuclear explosion, at any place under its jurisdiction or control: (a) in

the atmosphere; beyond its limits, including outer space; or under water, including territorial waters or high seas;”).

¹⁵⁷ OUTER SPACE TREATY art. IV (“States Parties to the Treaty undertake not to place in orbit around the Earth any

objects carrying nuclear weapons or any other kinds of weapons of mass destruction, install such weapons on

celestial bodies, or station such weapons in outer space in any other manner.”).

¹⁵⁸ See I NANDASIRI JASENTULIYANA & ROY S. LEE, MANUAL ON SPACE LAW 13-14 (1979) (“The phrase ‘orbit

around the earth’ in the first paragraph of this Article means that an object must be placed in a full orbit around the

earth before it comes within the prohibition of the Treaty. Therefore an object in a fractional orbit or suborbital

flight is not intended to be covered. This was the clear intention of the drafters of this Article.”).

¹⁵⁹ Staff Report prepared for the use of the Committee on Aeronautical and Space Sciences, United States Senate,

Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the

Moon and Other Celestial Bodies: Analysis and Background Data, 26 (Mar. 1967) (“The treaty does not change the

earthly situation with regard to ICBM’s, but seeks to achieve on celestial bodies a form of demilitarization which is

deemed feasible from military and political viewpoints.”).

¹⁶⁰ For example, Treaty Between the United States of America and the Union of Soviet Socialist Republics on the

Reduction and Limitation of Strategic Offensive Arms, Jul. 31, 1991, U.S.-USSR, Article V(18)(c), S. TREATY DOC.

NO. 102-20, which expired December 5, 2009.

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In addition, this rule in Article IV of the Outer Space Treaty does not establish any

prohibitions with respect to weapons that are not weapons of mass destruction (e.g., anti-satellite

laser weapons or other conventional weapons).¹⁶¹

14.10.3.2 Restrictions on Military Activities on the Moon and Other Celestial

Bodies. Article IV of the Outer Space Treaty places certain prohibitions on military activities on

the moon and other celestial bodies: (1) the establishment of military bases, installations, and

fortifications; and (2) the testing of any type of weapons; and (3) the conduct of military

maneuvers.¹⁶²

These activities are prohibited only on the moon and other celestial bodies, not in outer

space itself.

Article IV also recognizes the unimpeded right to: (1) the use of military personnel for

scientific research or other peaceful purposes on outer space missions; and (2) the use of any

equipment or facility necessary for the peaceful exploration of the moon and other celestial

bodies.¹⁶³

14.10.4 General Use of Outer Space for Peaceful Purposes. The United States has

expressed the view that outer space should be used only for peaceful purposes.¹⁶⁴ This view is

consistent with the Preamble to the Outer Space Treaty.¹⁶⁵

The United States has interpreted use of outer space for “peaceful purposes” to mean

“non-aggressive and beneficial” purposes consistent with the Charter of the United Nations and

¹⁶¹ David A. Koplow, ASAT-isfaction: Customary International Law and the Regulation of Anti-Satellite Weapons,

30 MICHIGAN JOURNAL OF INTERNATIONAL LAW 1187, 1198 (2009) (“This provision does not impede the stationing

of non-nuclear weapons (including conventional ASAT weapons) in space, nor does it affect a nuclear weapon that

makes only a temporary transit of outer space, as when propelled by an intercontinental ballistic missile (ICBM)

toward its target, rather than being ‘stationed’ in space.”).

¹⁶² OUTER SPACE TREATY art. IV (“The moon and other celestial bodies shall be used by all States Parties to the

Treaty exclusively for peaceful purposes. The establishment of military bases, installations and fortifications, the

testing of any type of weapons and the conduct of military maneuvers on celestial bodies shall be forbidden.”).

¹⁶³ OUTER SPACE TREATY art. IV (“The use of military personnel for scientific research or for any other peaceful

purposes shall not be prohibited. The use of any equipment or facility necessary for peaceful exploration of the

moon and other celestial bodies shall also not be prohibited.”).

¹⁶⁴ See, e.g., National Space Policy of the United States of America 3 (Jun. 28, 2010) (“All nations have the right to

explore and use space for peaceful purposes, and for the benefit of all humanity, in accordance with international

law. Consistent with this principle, ‘peaceful purposes’ allows for space to be used for national and homeland

security activities.”); Albert Gore, Sr., U.S. Representative to the United Nations, U.N. General Assembly, 17th

Sess., 1289th Mtg., U.N. Doc. A/C.1/PV.1289 (1962) (“It is the view of the United States that outer space should be

used only for peaceful - that is non-aggressive and beneficial - purposes. The question of military activities in

space cannot be divorced from the question of military activities on Earth. To banish these activities in both

environments we must continue our efforts for general and complete disarmament with adequate safeguards. Until

this is achieved, the test of any space activities must not be whether it is military or non-military, but whether or not

it is consistent with the United Nations Charter and other obligations of law.”).

¹⁶⁵ OUTER SPACE TREATY preamble (“Recognizing the common interest of all mankind in the progress of the

exploration and use of outer space for peaceful purposes,”).

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other international law.¹⁶⁶ This interpretation of “peaceful purposes” is similar to the

interpretation given to the reservation of the high seas for “peaceful purposes” in the LOS

Convention.¹⁶⁷

For example, observation or information-gathering from satellites in space is not an act of

aggression under the Charter of the United Nations and, thus, would be a use of space for

peaceful purposes.¹⁶⁸ Similarly, lawful military activities in self-defense (e.g., missile early

warning, use of weapon systems) would be consistent with the use of space for peaceful

purposes, but aggressive activities that violate the Charter of the United Nations would not be

permissible.¹⁶⁹

Article IV of the Outer Space Treaty provides that “[t]he moon and other celestial bodies

shall be used by all States Parties to the Treaty exclusively for peaceful purposes.”¹⁷⁰ Article IV

specifies restrictions on military operations on the moon and other celestial bodies.¹⁷¹

14.10.5 Outer Space Treaty Provisions on Cooperation, Mutual Assistance, and

Potentially Harmful Interference. Article IX of the Outer Space Treaty provides that in the

exploration and use of outer space, States Parties shall be guided by the principle of cooperation

and mutual assistance and shall conduct all their activities in outer space with due regard to the

¹⁶⁶ Senator Albert Gore, Sr., Treaty on Outer Space: Hearings Before the Committee on Foreign Relations, U.S.

Senate, 90th Congress, First Session, 59 (Mar. 13, 1967) (“We interpret peaceful purposes as being non-aggressive

and beneficial.”). See also Staff Report prepared for the use of the Committee on Aeronautical and Space Sciences,

United States Senate, Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer

Space, Including the Moon and Other Celestial Bodies: Analysis and Background Data, 11 (Mar. 1967) (“In

Russian, the word for ‘military’ essentially means warlike rather than pertaining to the armed services of a country;

in the United States, ‘peaceful’ is not regarded as the opposite of ‘military’—we think of ‘peaceful’ as ‘not

aggressive.’”); CARL Q. CHRISTOL, THE MODERN INTERNATIONAL LAW OF OUTER SPACE 22 (1982) (“The

expression ‘peaceful purposes’ is a legal term of art. At the beginning of the Space age several views were

advanced as to its meaning, with one view being that military activities in the space environment could not be and

were not peaceful. The opposing position, which today has gained general acceptance, is that nonaggressive

military uses are peaceful. Thus, ‘peaceful’ has come to mean general space activity that is beneficial to and in the

interests of all countries.”).

¹⁶⁷ Refer to § 13.1.1 (The Law of the Sea During Armed Conflict).

¹⁶⁸ See Albert Gore, Sr., U.S. Representative to the United Nations, U.N. General Assembly, 17th Sess., 1289th

Mtg., U.N. Doc. A/C.1/PV.1289 13 (1962) (“[A]ny nation may use space satellites for such purposes as observation

and information-gathering. Observation from space is consistent with international law, just as is observation from

the high seas.”); Report by the Committee on Satellite Reconnaissance Policy, attached to Jul. 2, 1962 memorandum

from Secretary Rusk to President Kennedy, excerpted in XXV FOREIGN RELATIONS OF THE UNITED STATES (1961-

1963), 951-59 (2001) (“(b) It is well established that areas subject to the jurisdiction of a state may be observed from

points outside that jurisdiction, e.g., from a ship on the high seas. Observation from outer space, which is not

subject to territorial claims, also cannot be considered to constitute a violation of international law.”).

¹⁶⁹ CARL Q. CHRISTOL, THE INTERNATIONAL LAW OF OUTER SPACE 114 (1966) (“It may be concluded that both

ballistic missiles, directly, and satellites, indirectly, have military utility. This does not automatically exclude them

from the category of peaceful uses, since defensive and deterrent capabilities serve the cause of peace. It is only

when such devices are intentionally used for aggressive purposes that they lose their peaceful status.”).

¹⁷⁰ OUTER SPACE TREATY art. IV (“The moon and other celestial bodies shall be used by all States Parties to the

Treaty exclusively for peaceful purposes.”).

¹⁷¹ Refer to § 14.10.3.2 (Restrictions on Military Activities on the Moon and Other Celestial Bodies).

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corresponding interests of all other States Parties.¹⁷² For example, States should conduct their

activities in space with due regard for the rights of other States to have their space systems pass

through, and conduct operations in, space without interference.

Article IX of the Outer Space Treaty also requires States Parties to undertake

“appropriate international consultations” before proceeding with any activity or experiment

planned by it or its nationals in outer space if that State Party has reason to believe that its

activity or experiment would cause potentially harmful interference with the activities of other

States Parties in the peaceful exploration and use of outer space.¹⁷³ Conversely, a State Party

that has reason to believe that an activity or experiment planned by another State Party in outer

space would cause potentially harmful interference with its activities in the peaceful exploration

and use of outer space may request consultation concerning the activity or experiment.¹⁷⁴

¹⁷² OUTER SPACE TREATY art. IX (“In the exploration and use of outer space, including the moon and other celestial

bodies, States Parties to the Treaty shall be guided by the principle of cooperation and mutual assistance and shall

conduct all their activities in outer space, including the moon and other celestial bodies, with due regard to the

corresponding interests of all other States Parties to the Treaty.”).

¹⁷³ OUTER SPACE TREATY art. IX (“If a State Party to the Treaty has reason to believe that an activity or experiment

planned by it or its nationals in outer space, including the moon and other celestial bodies, would cause potentially

harmful interference with activities of other States Parties in the peaceful exploration and use of outer space,

including the moon and other celestial bodies, it shall undertake appropriate international consultations before

proceeding with any such activity or experiment.”).

¹⁷⁴ OUTER SPACE TREATY art. IX (“A State Party to the Treaty which has reason to believe that an activity or

experiment planned by another State Party in outer space, including the moon and other celestial bodies, would

cause potentially harmful interference with activities in the peaceful exploration and use of outer space, including

the moon and other celestial bodies, may request consultation concerning the activity or experiment.”).

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XV - The Law of Neutrality

Chapter Contents

15.1 Introduction

15.2 Application of the Law of Neutrality

15.3 Overview of the Neutrality Law’s Framework of Reciprocal Rights and

Duties

15.4 Remedies for Violations of Neutrality Law

15.5 Prohibition on the Use of Neutral Territory as a Base of Operations

15.6 Neutral Persons

15.7 Neutral Waters

15.8 Passage of Belligerent Vessels and Aircraft Through International Straits and

Archipelagic Sea Lanes

15.9 Additional Rules Applicable to Neutral Ports, Roadsteads, and Internal

Waters

15.10 Neutral Airspace

15.11 Belligerent Right of Angary

15.12 Neutral Commerce and Carriage of Contraband

15.13 Belligerent Right of Visit and Search of Merchant Vessels and Civil

Aircraft

15.14 Acquisition of Enemy Character by Neutral-Flagged Merchant Vessels and

Neutral-Marked Civil Aircraft

15.15 Capture of Neutral Vessels and Aircraft

15.16 Belligerent Forces Taking Refuge in Neutral Territory

15.17 POWs or Internees Brought to, or Received by, a Neutral State

15.18 Authorized Passage of Wounded and Sick Combatants Through Neutral

Territory

15.1 INTRODUCTION

This Chapter addresses the law of neutrality.

Issues of neutrality law can raise questions of national policy regarding an armed

conflict.¹ In U.S. practice, such national policies would be developed through the National

Security Council (NSC) process by the Department of State and other departments and agencies

represented on the National Security Council.²

Some of the rules described in this Chapter were formulated long ago. Moreover, treaties

concerning the law of neutrality might, by their terms, apply only to a limited set of international

¹ Refer to § 15.2.1.1 (Application of the Law of Neutrality and the National Policies of States Towards an Armed

Conflict).

² See, e.g., Barack Obama, Presidential Policy Directive - 1, Organization of the National Security Council System,

Feb. 13, 2009.

929

armed conflicts, and the rules prescribed in those treaties might not reflect customary

international law.³ In addition, it may be important to consider the implications of more recent

treaties that might be applicable to a specific legal issue. In particular, the Charter of the United

Nations may, in certain respects, be understood to be consistent with, and, in other respects, to

modify, rules reflected in the law of neutrality.⁴

15.1.1 Matters Addressed by the Law of Neutrality. The law of neutrality prescribes the

legal relationship between belligerent States and neutral States. The law of neutrality regulates

relations between: (1) belligerent States, vessels, aircraft, and persons; and (2) neutral States,

vessels, aircraft, and persons. Under the law of neutrality, these categories of belligerents and

neutrals have corresponding rights, duties, and liabilities. Special rules have been developed to

address situations on land, at sea, and in the air.

Certain rules found in the law of neutrality have also been applied in other contexts that

are closely analogous, such as a State’s duties to prevent a non-State armed group’s use of its

territory for hostile expeditions against another State.⁵

15.1.2 Classification of States as Belligerent, Neutral, or Non-Belligerent.

15.1.2.1 Belligerent State. Belligerent State refers to a State that is engaged in an

international armed conflict, whether or not a formal declaration of war has been made.⁶

15.1.2.2 Neutral State. Neutral State refers to a State that is not taking part in the

armed conflict.⁷ In some cases, States formally state their neutral status in relation to an armed

conflict.⁸

15.1.2.3 Non-Belligerent State. The term “non-belligerent” or “non-belligerent

State” has been used to refer to a State that is not participating in the armed conflict. The term

“non-belligerent Power” is used in the 1949 Geneva Conventions.⁹

In addition, the term “non-belligerent” has been used to refer to States that sought to

refrain from active participation in hostilities, but that did not adhere to the duties of strict

³ Refer to § 15.1.4 (Application of Treaties on Neutrality and Customary International Law).

⁴ Refer to § 15.2.3 (The Law of Neutrality Under the Charter of the United Nations).

⁵ Refer to § 17.18 (Non-Intervention and Neutral Duties in NIAC).

⁶ Refer to § 3.4.2.1 (Reasons for States to Seek to Deny the Existence of Hostilities).

⁷ 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION preamble (“Considering that neutrality is the juridical

situation of states which do not take part in the hostilities, and that it creates rights and imposes obligations of

impartiality, which should be regulated;”).

⁸ Refer to § 15.2.1.4 (Proclamations of Neutrality and Other Notifications of Neutral Status).

⁹ Refer to § 15.16.3.1 (Provision of POW Treatment and Application of the GWS and GWS-Sea by Analogy).

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impartiality to which neutrals have traditionally been required to adhere.¹⁰ Such departure from

the traditional duties of impartiality has, at times, been controversial.¹¹

15.1.3 Purpose of the Law of Neutrality. The law of neutrality seeks to preserve friendly

relations between belligerent and neutral States by permitting States to avoid taking sides in an

armed conflict.¹² The law of neutrality also seeks to prevent additional States from being drawn

into an armed conflict by establishing a clear distinction between belligerent and neutral States.¹³

In particular, the law of neutrality seeks to minimize the effects of armed conflict on States that

are not party to the conflict, including by lessening the effect of war on neutral commerce.

15.1.4 Application of Treaties on Neutrality and Customary International Law. The

treaties that address neutrality may be limited in their application as a matter of treaty law, but

provisions of these treaties may reflect customary international law.

For example, many of the treaties that address the law of neutrality were concluded

before World War II, and have not been universally ratified by States.¹⁴ Moreover, certain

treaties only apply between the Parties to the treaty and, in some cases, only if all the belligerent

States are also Parties to the treaty.¹⁵ The principles reflected in those treaties, however, may

still be applicable insofar as they reflect customary international law, even if they do not apply as

a matter of treaty law.¹⁶ However, if the factual circumstances of the current context are quite

different from those underlying the formulation of the original treaty rule, it may be incorrect to

¹⁰ TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 192 (“Thus one of the marked developments of the second

World War was the emergence of so-called ‘nonbelligerency,’ a term used to indicate the position of states that

refrained from active participation in hostilities while at the same time abandoning the duties heretofore imposed

upon non-participants.”); id. at 198 (“It has already been observed that to the extent that this term has not been used

merely as a synonym for the usual position occupied by non-participants it has served to indicate varying degrees of

departure from the duties traditionally consequent upon a status of non-participation in war.”).

¹¹ Refer to § 15.2.2 (Qualified Neutrality).

¹² Carl Salans, Deputy Legal Adviser, Department of State, comment to R.R. Baxter, The Legal Consequences of the

Unlawful Use of Force under the Charter, 62 PROCEEDINGS OF THE AMERICAN SOCIETY OF INTERNATIONAL LAW AT

ITS ANNUAL MEETING 68, 76 (1968) (“When armed conflict occurs, the purpose of international law ought to be to

limit the scope of the conflict. This is also a purpose of the Charter. The law of neutrality serves that purpose.

Small states, like Cambodia, would find themselves quickly engulfed in conflict if they had to act on a determination

that one side or the other in hostilities was acting unlawfully. And nuclear states run another kind of risk if they

have to take sides in every conflict.”).

¹³ Michael Bothe, The Law of Neutrality, in DIETER FLECK, THE HANDBOOK OF HUMANITARIAN LAW IN ARMED

CONFLICTS 486 (¶1101) (1999) (“By establishing a clear distinction between neutral states and states parties to the

conflict, international law prevents more states from being drawn into the conflict.”).

¹⁴ See, e.g., 1928 PAN AMERICAN NEUTRALITY CONVENTION; HAGUE V; HAGUE XIII.

¹⁵ See, e.g., HAGUE V art. 20 (“The provisions of the present Convention do not apply except between Contracting

Powers and then only if all the belligerents are parties to the Convention.”); HAGUE XIII art. 28 (“The provisions of

the present Convention do not apply except to the contracting Powers, and then only if all the belligerents are parties

to the Convention.”). Consider Declaration respecting maritime law signed by the Plenipotentiaries of Great

Britain, Austria, France, Prussia, Russia, Sardinia, and Turkey, assembled in Congress at Paris, Apr. 16, 1856,

reprinted in 1 AJIL SUPPLEMENT: OFFICIAL DOCUMENTS 89, 90 (1907) (“The present Declaration is not and shall

not be binding, except between those Powers who have acceded, or shall accede to it.”).

¹⁶ Refer to § 1.8.1 (Relationship Between Treaties and Customary International Law).

931

assume that the particular treaty rule reflects (or should reflect) a rule of customary international

law applicable to the current factual circumstances.

15.1.5 Domestic Neutrality Laws. States may have domestic legislation relating to the

law of neutrality.

In some cases, these statutes implement a State’s obligations under the law of neutrality,

such as its obligations as a neutral to prevent the arming of belligerent warships in neutral

ports.¹⁷ These statutes may also serve to implement a State’s international obligations outside

the context of international armed conflict, such as its peacetime obligations to prevent its

territory from being used as a base of operations for hostile expeditions against friendly States.¹⁸

Domestic statutes may also implement the rights of States under the law of neutrality,

such as the right of belligerents to conduct captures.¹⁹

Domestic neutrality statutes may also help implement a State’s national policy with

respect to neutrality. The law of neutrality permits neutral States a degree of policy discretion

with respect to an armed conflict.²⁰ Some neutrality treaties recognize such domestic

legislation.²¹ Such legislation, however, must be applied impartially among belligerents.²² In

¹⁷ For example, 18 U.S.C. § 961 (“Whoever, within the United States, increases or augments the force of any ship of

war, cruiser, or other armed vessel which, at the time of her arrival within the United States, was a ship of war,

cruiser, or armed vessel, in the service of any foreign prince or state, or of any colony, district, or people, or

belonging to the subjects or citizens of any such prince or state, or of any colony, district, or people, the same being

at war with any foreign prince or state, or of any colony, district, or people, with whom the United States is at peace,

by adding to the number of guns of such vessel, or by changing those on board of her for guns of a larger caliber, or

by adding thereto any equipment solely applicable to war, shall be fined under this title or imprisoned not more than

one year, or both.”).

¹⁸ For example, 18 U.S.C. § 960 (“Whoever, within the United States, knowingly begins or sets on foot or provides

or prepares a means for or furnishes the money for, or takes part in, any military or naval expedition or enterprise to

be carried on from thence against the territory or dominion of any foreign prince or state, or of any colony, district,

or people with whom the United States is at peace, shall be fined under this title or imprisoned for not more than

three years, or both.”). Refer to § 17.18 (Non-Intervention and Neutral Duties in NIAC).

¹⁹ For example, 10 U.S.C. § 7651 (“(a) This chapter applies to all captures of vessels as prize during war by

authority of the United States or adopted and ratified by the President. However, this chapter does not affect the

right of the Army or the Air Force, while engaged in hostilities, to capture wherever found and without prize

procedures--(1) enemy property; or (2) neutral property used or transported in violation of the obligations of neutrals

under international law.”).

²⁰ Cordell Hull, Secretary of State, Statement at Department of State Press Conference, Sept. 21, 1939, 1

DEPARTMENT OF STATE BULLETIN 280 (Sept. 23, 1939) (“I think that you will find from a careful analysis of the

underlying principles of the law of neutrality that this Nation, or any neutral nation, has a right during a war to

change its national policies whenever experience shows the necessity for such change for the protection of its

interests and safety. I do not mean to be understood as saying that such action may be taken at the behest or in the

interests of one of the contending belligerents, it being understood, of course, that any measures taken shall apply

impartially to all belligerents.”).

²¹ For example, 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art. 5 (“When, according to the

domestic law of the neutral state, the ship may not receive fuel until twenty-four hours after its arrival in port, the

period of its stay may be extended an equal length of time.”).

932

addition, a State may have an obligation to notify other States of its domestic neutrality

statutes.²³

15.2 APPLICATION OF THE LAW OF NEUTRALITY

The application of the law of neutrality may depend on a State’s national policy towards

an armed conflict. A State’s obligations under jus ad bellum, including its obligations under the

Charter of the United Nations, may alter significantly its rights and duties under the law of

neutrality.

15.2.1 Armed Conflict and the Application of the Law of Neutrality.

15.2.1.1 Application of the Law of Neutrality and the National Policies of States

Towards an Armed Conflict. Whether the law of neutrality governs a State’s relations with

belligerents in an armed conflict may depend on that State’s national policy towards that armed

conflict.²⁴ For example, if an armed conflict occurs, a State may choose to join the armed

conflict, in which case it would no longer be neutral and the law of war rather than the law of

neutrality would govern its relations with opposing belligerents.²⁵ Similarly, if two States

conduct hostilities against one another, but refuse to recognize a state of armed conflict, third

States may reject this position and invoke the law of neutrality to protect their rights in relation

to the armed conflict.²⁶ In addition, outside States that recognize the belligerency of a rebel

faction in a civil war may choose to apply the law of neutrality in their relations with the rebel

faction and with the government.²⁷

²² HAGUE XIII preamble (“Seeing that it is desirable that the Powers should issue detailed enactments to regulate the

results of the attitude of neutrality when adopted by them; Seeing that it is, for neutral Powers, an admitted duty to

apply these rules impartially to the several belligerents;”).

²³ HAGUE XIII art. 27 (“The Contracting Powers shall communicate to each other in due course all Laws,

Proclamations, and other enactments regulating in their respective countries the status of belligerent warships in

their ports and waters, by means of a communication addressed to the Government of the Netherlands, and

forwarded immediately by that Government to the other Contracting Powers.”).

²⁴ Compare § 3.4.1 (Intent-Based Test for Applying Jus in Bello Rules).

²⁵ Michael Bothe, The Law of Neutrality, in DIETER FLECK, THE HANDBOOK OF HUMANITARIAN LAW IN ARMED

CONFLICTS 489 (¶1104) (1999) (“Traditional international law left to each state the sovereign decision of whether, at

the outbreak of a conflict between other states, it would participate or remain neutral. … The distinction between

participation and neutrality is a political, not military, decision. Where the law of neutrality requires decisions to be

taken by military command, the government concerned must give political guidance and clarify the position which it

takes in relation to a particular conflict.”).

²⁶ TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 199-200 (“Unlike the law governing the mutual behavior of

combatants, a large part of which may be considered operative in any international armed conflict, the rules

regulating the behavior of neutrals and belligerents remain strictly dependent for their operation upon the existence

of a state of war. It may be, however, that states engaged in armed conflict are unwilling to issue a declaration of

war or even to acknowledge the existence of a state of war. In such situations it would appear that the decision as to

whether or not to recognize the existence of a state of war, and thereby to bring into force the law of neutrality, must

rest principally with third states. The attitude of the parties engaged in armed conflict need not prove decisive for

third states, the latter being at liberty either to accept the position of the contestants (i.e., the position that war does

not exist) or to reject this position and to invoke the law of neutrality.”).

²⁷ Refer to § 3.3.3.1 (Recognition by Outside States of a Rebel Faction as a Belligerent in a Civil War).

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15.2.1.2 Application of Certain Duties of Neutral States Only in Certain

International Armed Conflicts. The duties of neutral States to refrain from certain types of

support to belligerent States do not apply to all armed conflicts to which jus in bello rules apply;

rather, such duties are only triggered in armed conflicts of a certain duration and intensity.²⁸

However, belligerent States have fundamental duties to respect the sovereignty of neutral States

in all international armed conflicts.²⁹

15.2.1.3 Application of Certain Rules in the Law of Neutrality Outside the Context

of International Armed Conflict. Certain parts of the law of neutrality may be viewed as

applicable outside the context of international armed conflict because certain duties that the law

of neutrality imposes are also found in international law applicable in peacetime. For example,

under the Charter of the United Nations, States must respect the sovereignty of other States.³⁰

Thus, States have duties of non-intervention and neutrality in relation to a non-international

armed conflict against a friendly State.³¹

15.2.1.4 Proclamations of Neutrality and Other Notifications of Neutral Status. A

formal declaration by nonparticipating States of their intention to adopt a neutral status generally

would not be required for a State to retain its neutral status.³² However, in light of the

importance of national policy in determining whether the law of neutrality is applicable, States

traditionally issued proclamations of neutrality in order to make known their neutral status in

relation to a conflict.³³ These proclamations of neutrality would state the determination of the

²⁸ See Michael Bothe, The Law of Neutrality, in DIETER FLECK, THE HANDBOOK OF HUMANITARIAN LAW IN ARMED

CONFLICTS 490-91 (¶1106) (1999) (“The law of neutrality leads to considerable modifications in the relationships

between the neutral and the belligerent states, for instance as to the admissibility of exports, the sojurn of warships

of the parties to the conflict in neutral waters, and the control of neutral trade. These fundamental changes are not

triggered by every armed incident, but require an armed conflict of a certain duration and intensity. Thus, the

threshold of application of the law of neutrality is probably higher than that for the rules of the law of war relating to

the conduct of hostilities and the treatment of prisoners, which are applicable also in conflicts of less intensity.”).

²⁹ See Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, 1996 I.C.J. (¶¶88-89) (“The Court will

now turn to the principle of neutrality which was raised by several States. In the context of the advisory proceedings

brought before the Court by the WHO concerning the Legality of the Use by a State of Nuclear Weapons in Armed

Conflict, the position was put as follows by one State: ‘The principle of neutrality, in its classic sense, was aimed at

preventing the incursion of belligerent forces into neutral territory, or attacks on the persons or ships of neutrals.

Thus: ‘the territory of neutral powers is inviolable’; ‘belligerents are bound to respect the sovereign rights of neutral

powers …’ ‘neutral states have equal interest in having their rights respected by belligerents …’. It is clear,

however, that the principle of neutrality applies with equal force to transborder incursions of armed forces and to the

transborder damage caused to a neutral State by the use of a weapon in a belligerent State.’ The principle so

circumscribed is presented as an established part of the customary international law. The Court finds that as in the

case of the principles of humanitarian law applicable in armed conflict, international law leaves no doubt that the

principle of neutrality, whatever its content, which is of a fundamental character similar to that of the humanitarian

principles and rules, is applicable (subject to the relevant provisions of the United Nations Charter), to all

international armed conflict, whatever type of weapons might be used.”) (citations omitted) (amendments in

original).

³⁰ Refer to § 1.11.3 (Prohibition on Certain Uses of Force).

³¹ Refer to § 17.18 (Non-Intervention and Neutral Duties in NIAC).

³² Compare § 3.4.2.1 (Reasons for States to Seek to Deny the Existence of Hostilities).

³³ For example, Franklin D. Roosevelt, Proclamation: Proclaiming the Neutrality of the United States in the War

Between Germany and France; Poland; and The United Kingdom, India, Australia and New Zealand, Sept. 5, 1939,

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State to observe the duties of neutrality and warn its nationals of the penalties they would incur

for joining or assisting a belligerent State.³⁴

Although the practice of issuing formal proclamations of neutrality has declined, States

have continued to make public statements of neutrality to indicate their national policy and legal

status in relation to an armed conflict.³⁵ States may also communicate their neutral status

through diplomatic channels or use other means they deem appropriate.

15.2.2 Qualified Neutrality. The United States has taken the position that certain duties

of neutral States may be inapplicable under the doctrine of qualified neutrality.

54 STAT. 2629 (“AND I do hereby give notice that all nationals of the United States and others who may claim the

protection of this government, who may misconduct themselves in the premises, will do so at their peril, and that

they can in no wise obtain any protection from the government of the United States against the consequences of their

misconduct.”); Woodrow Wilson, Proclamation, Aug. 18, 1914, 38 STAT. 2015 (“Whereas the United States is in

fact aware of the existence of a state of war between Belgium and Germany; And Whereas the United States is on

terms of friendship and amity with the contending powers, and with the persons inhabiting their several

dominions;”); George Washington, Proclamation of Neutrality, Apr. 22, 1793, reprinted in 32 THE WRITINGS OF

GEORGE WASHINGTON FROM THE ORIGINAL MANUSCRIPT SOURCES 1745-1799, 430-31 (1939) (“Whereas it appears

that a state of war exists between Austria, Prussia, Sardinia, Great Britain, and the United Netherlands, on the one

part, and France on the other; and the duty and interest of the United States require, that they should with sincerity

and good faith adopt and pursue a conduct friendly and impartial towards the belligerent powers: I have therefore

thought fit by these presents, to declare the disposition of the United States to observe the conduct aforesaid towards

those powers respectively; and to exhort and warn the citizens of the United States carefully to avoid all acts and

proceedings whatsoever, which may in any manner tend to contravene such disposition. And I do hereby also make

known, that whosoever of the citizens of the United States shall render himself liable to punishment or forfeiture

under the law of nations, by committing, aiding or abetting hostilities against any of the said powers, or by carrying

to any of them, those articles which are deemed contraband by the modern usage of nations, will not receive the

protection of the United States against such punishment or forfeiture; and further that I have given instructions to

those officers to whom it belongs, to cause prosecutions to be instituted against all persons, who shall, within the

cognizance of the Courts of the United States, violate the law of nations, with respect to the powers at war, or any of

them.”).

³⁴ 1956 FM 27-10 (Change No. 1 1976) ¶514 (“When war occurs, neutral States usually issue proclamations of

neutrality, in which they state their determination to observe the duties of neutrality and warn their nationals of the

penalties they incur for joining or assisting a belligerent.”).

³⁵ For example, FINAL REPORT ON THE PERSIAN GULF WAR 626 (“Iran and Jordan each issued proclamations of

neutrality during the Persian Gulf crisis and, as described, refrained from active participation in the war.”); Ronald

Reagan, Written Responses to Questions Submitted by Al-Qabas of Kuwait, May 12, 1987, 1987-I PUBLIC PAPERS

OF THE PRESIDENTS 529 (“The United States is neutral in the Iran-Iraq war.”); Jimmy Carter, Situation in Iraq and

Iran: Remarks Concerning the Conflict, Sept. 24, 1980, 1980-81-II PUBLIC PAPERS OF THE PRESIDENTS 1921, 1922

(“Let me repeat that we have not been and we will not become involved in the conflict between Iran and Iraq.”);

Royal Government of Laos, Statement of Jul. 9, 1962, reprinted in Burma, Cambodia Canada, People’s Republic of

China, Democratic Republic of Viet-Nam, etc., Declaration on the Neutrality of Laos, Jul. 23, 1962, 456 UNTS 301,

302-03 (“The Royal Government of Laos, Being resolved to follow the path of peace and neutrality in conformity

with the interests and aspirations of the Laotian people, as well as the principles of the Joint Communiqué of Zurich

dated June 22, 1961, and of the Geneva Agreements of 1954, in order to build a peaceful, neutral, independent,

democratic, unified and prosperous Laos, Solemnly declares that: … (4) It will not enter into any military alliance or

into any agreement, whether military or otherwise, which is inconsistent with the neutrality of the Kingdom of Laos;

it will not allow the establishment of any foreign military base on Laotian territory, nor allow any country to use

Laotian territory for military purposes or for the purposes of interference in the internal affairs of other countries,

nor recognise the protection of any alliance or military coalition, including SEATO;”).

935

The law of neutrality has traditionally required neutral States to observe a strict

impartiality between parties to a conflict, regardless of which State was viewed as the aggressor

in the armed conflict.³⁶ However, after treaties outlawed war as a matter of national policy, it

was argued that neutral States could discriminate in favor of States that were victims of wars of

aggression.³⁷ Thus, before its entry into World War II, the United States adopted a position of

“qualified neutrality” in which neutral States had the right to support belligerent States that had

been the victim of flagrant and illegal wars of aggression.³⁸ This position was controversial.³⁹

15.2.3 The Law of Neutrality Under the Charter of the United Nations. The Charter of

the United Nations may, in certain respects, be understood to be consistent with, and, in other

respects, to modify, rules reflected in the law of neutrality.

³⁶ Refer to § 15.3.2 (Neutral Duties -- Abstention From Participation in Hostilities and Impartial Conduct Toward

Contending Parties).

³⁷ LAUTERPACHT, II OPPENHEIM’S INTERNATIONAL LAW 221 (§61) (“Similarly, it is open to neutral States as a matter

of legal right to give effect to their moral obligation to discriminate against the aggressor and to deny him, in their

discretion, the right to exact from neutrals a full measure of impartiality. In some cases neutral States may, having

regard to their own safety and the desire not to be involved in the war, continue to accord impartial treatment to the

aggressor. But they need not do so wherever they feel in the position actively to assert the principle, as did the

United States and other States before entering the Second World War, that the historic foundation of neutrality as an

attitude of absolute impartiality has disappeared with the renunciation and the abolition of war as an instrument of

national policy. With regard to States bound by the obligations of the Charter of the United Nations that legal

faculty and that moral obligation assume the clear complexion of a legal duty.”).

³⁸ Address of Robert H. Jackson, Attorney General of the United States, Inter-American Bar Association, Havana,

Cuba, March 27, 1941, 35 AJIL 348, 353-54 (1941) (“Present aggressive wars are civil wars against the

international community. Accordingly, as responsible members of that community, we can treat victims of

aggression in the same way we treat legitimate governments when there is civil strife and a state of insurgency—that

is to say, we are permitted to give to defending governments all the aid we choose. In the light of the flagrancy of

current aggressions, which are apparent on their face, and which all right thinking people recognize for what they

are, the United States and other states are entitled to assert a right of discriminatory action by reason of the fact that,

since 1928 so far as it is concerned, the place of war and with it the place of neutrality in the international legal

system have no longer been the same as they were prior to that date.”).

³⁹ See, e.g., Edwin Borchard, War, Neutrality and Non-Belligerency, 35 AJIL 618 (1941) (“At Havana on March 27,

1941, Attorney General Jackson delivered an address designed to prove that as a matter of law the United States was

now obliged to render to England (and presumably others) all aid ‘short of war,’ while ‘at the same time it is the

declared determination of the government to avoid entry into the war as a belligerent.’ Apparently convinced that

United States military aid to one belligerent alone cannot be justified by the traditional international law, the

Attorney General feels obliged first to explode as obsolete the international law conceptions of war and neutrality of

the past two centuries, culminating in The Hague Conventions, and to maintain that a new international law has now

been revealed in the Covenant of the League of Nations, the Kellogg Pact, the Budapest ‘Articles of Interpretation’

of 1934, and the Argentine Anti-War Treaty of 1933, all of which are alleged to make discrimination the new way of

life for neutrals. The legislation of Congress requiring impartiality is not accorded even honorable mention. The

‘new international law’ is thus found in the vague and illusory monuments to the myth called ‘collective security,’

which crumbled under the impact of the first European crisis. It should be no surprise to the Attorney General that

many international lawyers do not share his views on international law or how international law is created, or follow

his unique construction of documents.”).

936

15.2.3.1 Consistency Between the Rules in the Law of Neutrality and the Charter

of the United Nations. In certain cases, the rules on the use of force prescribed in the Charter of

the United Nations would be understood to be consistent with rules in the law of neutrality.⁴⁰

For example, a neutral State’s acts of participation in a war of aggression against another

member of the United Nations would likely violate not only its duties under the law of

neutrality,⁴¹ but also the Charter’s prohibition on the unlawful use of force.⁴²

In the past, the law of neutrality was often viewed as not regulating a State’s decision as

to whether to adopt a position of neutrality or hostility towards another State.⁴³ Thus, under this

view, the requirements of the law of neutrality could have been avoided by neutral States if they

decided to enter the war or by belligerent States if they chose to declare war on a neutral.⁴⁴ The

Charter of the United Nations clarifies that such decisions to resort to force may not be made

without a proper legal basis.⁴⁵ Thus, insofar as provisions of the Charter are coincident with

certain rules in the law of neutrality, such requirements of the Charter may not be evaded in the

⁴⁰ See, e.g., BRUNO SIMMA, THE CHARTER OF THE UNITED NATIONS: A COMMENTARY 673 (1994) (“For the purpose

of responding to an ‘armed attack’, the state acting in self-defence is allowed to trespass on foreign territory, even

when the attack cannot be attributed to the state from whose territory it is proceeding. It does not follow from the

fact that the right of self-defence pursuant to Art. 51 is restricted to the case of an ‘armed attack’ that defensive

measures may only affect the ‘attacker’. Thus it is compatible with Art. 51 and the laws of neutrality when a

warring state fights hostile armed forces undertaking an attack from neutral territory on the territory of the neutral

state, provided that the state concerned is either unwilling or unable to curb the ongoing violation of its neutrality.”).

⁴¹ Refer to § 15.3.2 (Neutral Duties -- Abstention From Participation in Hostilities and Impartial Conduct Toward

Contending Parties).

⁴² Refer to § 1.11.3 (Prohibition on Certain Uses of Force).

⁴³ See Editorial Comment: The Hague Conventions and the Neutrality of Belgium and Luxemburg, 9 AJIL 959

(1915) (“[Articles of the Hague V] do not, however, guarantee neutrality, nor do they prevent a state from declaring

war against a state wishing to remain neutral, which thus becomes a belligerent and loses the benefit of the

convention. If the Hague conventions were violated by Germany in this matter it would appear to be a violation of

the spirit, not of the letter, and indeed it is difficult to maintain that there was a violation even of the spirit, because

international law in its present development apparently allows nations to go to war whenever they please, and the

Hague conventions do not modify or abridge this provision of the law of nations.”).

⁴⁴ See John Delatre Falconbridge, The Right of a Belligerent to Make War Upon a Neutral, 4 TRANSACTIONS OF THE

GROTIUS SOCIETY 204, 209-11 (1918) (“The fifth [Hague] convention [of 1907] does not relate to the question of

the right to convert the relation of belligerent and neutral into that of belligerent and belligerent, but simply defines

the rights and obligations incidental to the former relation. … The fundamental proposition which has been left

untouched by The Hague Conventions is that by the existing rules of international law one State may declare war

against another State without any justifiable casus belli, and it commits no breach of law in so doing if it complies

with the requirements relating to the declaration of war. Its action may be immoral, but it is not illegal unless there

is a treaty forbidding such action (as there was in the case of Belgium).”).

⁴⁵ See Michael Bothe, The Law of Neutrality, in DIETER FLECK, THE HANDBOOK OF HUMANITARIAN LAW IN ARMED

CONFLICTS 489 (¶1104) (1999) (“Traditional international law left to each state the sovereign decision of whether, at

the outbreak of a conflict between other states, it would participate or remain neutral. … At the outbreak of a

conflict between two other states, a state is still free to participate or to remain neutral. Modern international law,

however, limits the freedom of decision as to which side on which a state may become involved. Support granted to

an aggressor is illegal, participation on the side of the victim of aggression, being collective self-defence, is

permissible.”).

937

way that arguably certain requirements of the law of neutrality previously could have been

evaded.

15.2.3.2 Modification of Rules in the Law of Neutrality. The Charter of the

United Nations and decisions by the U.N. Security Council may, in certain circumstances,

qualify rights and obligations under the law of neutrality.⁴⁶

For example, under the Charter of the United Nations, States may have obligations to

support military operations that have been authorized by the U.N. Security Council.⁴⁷ In such

circumstances, the obligations under the Charter would prevail over the obligations under the law

of neutrality.⁴⁸ For example, a State that is not participating in the conflict that received in its

territory military forces operating pursuant to a U.N. Security Council resolution might be

required to return them, rather than to intern them under the law of neutrality.⁴⁹ Moreover, U.N.

Security Council resolutions may obligate States to take measures that would not be required by

neutrality law. For example, the U.N. Security Council may require States to impose restrictions

on private conduct within their jurisdiction, such as to prevent private individuals from selling

weapons to certain States or non-State armed groups.⁵⁰

⁴⁶ 1956 FM 27-10 (Change No. 1 1976) ¶513 (“Although these provisions of the Charter have not made it

impossible for a State to remain neutral, the obligations which the Charter imposes have to a certain extent qualified

the rights of States in this respect.”).

⁴⁷ Refer to § 1.11.2.1 (U.N. Member State Obligations With Respect to U.N. Security Council Decisions).

⁴⁸ For example, FINAL REPORT ON THE PERSIAN GULF WAR 626 (“Neutrality in the Persian Gulf War was controlled

in part by the 1907 Hague V Convention; but traditional concepts of neutral rights and duties are substantially

modified when, as in this case, the United Nations authorizes collective action against an aggressor nation. It was

the US position during the Persian Gulf crisis that, regardless of assertions of neutrality, all nations were obligated to

avoid hindrance of Coalition operations undertaken pursuant to, or in conjunction with, UNSC decisions, and to

provide whatever assistance possible. By virtue of UNSC Resolution 678 (29 November), members were requested

‘to provide appropriate support for the actions undertaken’ by nations pursuant to its authorization of use of all

necessary means to uphold and implement prior resolutions. The language of UNSC Resolution 678 is consistent

with Articles 2(5), 2(6), 25, and 49 of the UN Charter.”).

⁴⁹ FINAL REPORT ON THE PERSIAN GULF WAR 628 (“Although the situation never arose, the United States advised

Iran that, in light of UNSC Resolution 678, Iran would be obligated to return downed Coalition aircraft and aircrew,

rather than intern them. This illustrates the modified nature of neutrality in these circumstances. It also was the US

position that entry into Iranian (or Jordanian) airspace to rescue downed aviators would be consistent with its

international obligations as a belligerent, particularly in light of Resolution 678.”).

⁵⁰ For example, U.N. SECURITY COUNCIL RESOLUTION 1970, U.N. Doc. S/RES/1970, ¶9 (Feb. 26, 2011) (“Decides

that all Member States shall immediately take the necessary measures to prevent the direct or indirect supply, sale or

transfer to the Libyan Arab Jamahiriya, from or through their territories or by their nationals, or using their flag

vessels or aircraft, of arms and related materiel of all types, including weapons and ammunition, military vehicles

and equipment, paramilitary equipment, and spare parts for the aforementioned, and technical assistance, training,

financial or other assistance, related to military activities or the provision, maintenance or use of any arms and

related materiel, including the provision of armed mercenary personnel whether or not originating in their

territories,”); U.N. SECURITY COUNCIL RESOLUTION 713, U.N. Doc S/RES/713 ¶6 (Sept. 25, 1991) (“Decides, under

Chapter VII of the Charter of the United Nations, that all States shall, for the purposes of establishing peace and

stability in Yugoslavia, immediately implement a general and complete embargo on all deliveries of weapons and

military equipment to Yugoslavia until the Council decides otherwise following consultation between the Secretary-

General and the Government of Yugoslavia;”).

938

15.2.4 Neutrality Under Regional and Collective Self-Defense Arrangements. Regional

and collective self-defense agreements may affect States’ rights to maintain a neutral status

because the States may be required to provide assistance or take military action in collective self-

defense until the U.N. Security Council has taken measures necessary to maintain international

peace and security.⁵¹ The obligations by a State under such an agreement may prevail over the

State’s right under the customary law of neutrality to be impartial among the belligerents and to

abstain from the armed conflict.

15.3 OVERVIEW OF THE NEUTRALITY LAW’S FRAMEWORK OF RECIPROCAL RIGHTS AND DUTIES

The law of neutrality establishes a framework of reciprocal rights and duties for neutrals

and belligerents.

15.3.1 Neutral Rights. Belligerent States are bound to respect the sovereign rights of

neutral States (e.g., the inviolability of a neutral State’s territory).⁵² The exercise by a neutral

State of its rights under the law of neutrality may not be considered an unfriendly act by either of

the belligerents.⁵³

15.3.1.1 Inviolability of Neutral Territory - Prohibition on Unauthorized Entry.

The territory of neutral States is inviolable.⁵⁴ The inviolability of neutral territory prohibits any

unauthorized entry into the territory of a neutral State, its territorial waters, or the airspace over

such areas by armed forces or instrumentalities of war.⁵⁵

15.3.1.2 Inviolability of Neutral Territory - Prohibition on Hostile Acts or Other

Violations of Neutrality. The inviolability of neutral territory also requires belligerent forces to

refrain from committing hostile acts or other acts that, if knowingly permitted by a neutral State,

would constitute a violation of neutrality in neutral territory (including neutral lands, neutral

⁵¹ Refer to § 1.11.5.5 (Right of Collective Self-Defense).

⁵² HAGUE XIII art. 1 (“Belligerents are bound to respect the sovereign rights of neutral Powers and to abstain, in

neutral territory or neutral waters, from any act which would, if knowingly permitted by any Power, constitute a

violation of neutrality.”); 1956 FM 27-10 (Change No. 1 1976) ¶512 (“It is the duty of belligerents to respect the

territory and rights of neutral States.”).

⁵³ HAGUE XIII art. 26 (“The exercise by a neutral Power of the rights laid down in the present convention can under

no circumstances be considered as an unfriendly act by one or other belligerent who has accepted the Articles

relating thereto.”).

⁵⁴ HAGUE V art. 1 (“The territory of neutral Powers is inviolable.”).

⁵⁵ 1956 FM 27-10 (Change No. 1 1976) ¶515 (“b. Application of Rule. The foregoing rule prohibits any

unauthorized entry into the territory of a neutral State, its territorial waters, or the airspace over such areas by troops

or instrumentalities of war.”).

939

waters, and neutral airspace).⁵⁶ For example, belligerent warships may not exercise the

belligerent right of visit and search, and may not capture vessels in neutral waters.⁵⁷

However, belligerent forces may use force in self-defense or as part of self-help

enforcement actions against enemy forces that have committed violations of neutrality when the

neutral State is unwilling or unable to address such violations.⁵⁸

15.3.2 Neutral Duties -- Abstention From Participation in Hostilities and Impartial

Conduct Toward Contending Parties. The principal duties of a neutral State are to abstain from

any participation in the conflict and to be impartial in conduct towards contending parties.⁵⁹

Certain other duties may be viewed as a consequence of these principal duties, but

different publicists have categorized these duties differently. For example, the duty of a neutral

State to refrain from supporting one side in the conflict may be viewed as a function of its duty

to abstain from participation in hostilities.⁶⁰ On the other hand, the duty of a neutral State to

refrain from supporting one side in the conflict may also be viewed as a result of its duty of

impartiality.⁶¹

The duties of a neutral State may also be classified in terms of: (1) abstention

(obligations to refrain from taking certain actions); (2) prevention (obligations to take certain

actions); and (3) acquiescence (obligations to accept certain actions by belligerents).⁶²

⁵⁶ 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art. 3 (“Belligerent states are obligated to refrain from

performing acts of war in neutral waters or other acts which may constitute on the part of the State that tolerates

them, a violation of neutrality.”); HAGUE XIII art. 1 (“Belligerents are bound to respect the sovereign rights of

neutral Powers and to abstain, in neutral territory or neutral waters, from any act which would, if knowingly

permitted by any Power, constitute a violation of neutrality.”).

⁵⁷ Refer to § 15.13.3 (Where Belligerents May Not Exercise the Right of Visit and Search); § 15.15 (Capture of

Neutral Vessels and Aircraft).

⁵⁸ Refer to § 15.4.2 (Belligerent Use of Self-Help When Neutral States Are Unable or Unwilling to Prevent

Violations of Neutrality).

⁵⁹ The Three Friends, 166 U.S. 1, 52 (1897) (“Neutrality, strictly speaking, consists in abstinence from any

participation in a public, private or civil war, and in impartiality of conduct toward both parties, … .”).

⁶⁰ Michael Bothe, The Law of Neutrality, in DIETER FLECK, THE HANDBOOK OF HUMANITARIAN LAW IN ARMED

CONFLICTS 485 (¶1101) (1999) (“The duty of non-participation means, above all, that the state must abstain from

supporting a party to the conflict. This duty not to support also means that the neutral state is under a duty not to

allow one party to the conflict to use the resources of the neutral state against the will of the opponent. Therefore,

the defence of neutrality is part of the duty of non-participation.”).

⁶¹ LAUTERPACHT, II OPPENHEIM’S INTERNATIONAL LAW 654 (§294) (“Since neutrality is an attitude of impartiality, it

excludes such assistance and succor to one of the belligerents as is detrimental to the other, and, further, such

injuries to the one as benefit the other. But it requires, on the other hand, active measures from neutral States. For

neutrals must prevent belligerents from making use of their neutral territories, and of their resources, for military and

naval purposes during the war.”).

⁶² TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 203 footnote 14 (“The duties of a neutral state may also be

classified—and frequently are so classified—as duties of abstention, prevention and acquiesence [sic] (or toleration).

Duties of abstention refer to acts the neutral state itself must refrain from performing; duties of prevention refer to

acts the commission of which within its jurisdiction the neutral is obligated to prevent; and, finally, duties of

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15.3.2.1 Duty to Refrain From Providing War-Related Goods and Services to

Belligerents. Neutral States have an obligation to refrain from providing war-related goods and

services to belligerents.⁶³ A neutral State is prohibited from supplying a belligerent State in any

manner, either directly or indirectly, with warships, ammunition, or war material of any kind.⁶⁴

The neutral State is also prohibited from providing money or loans to a belligerent State.⁶⁵

A neutral State also has a duty to refrain from placing its various governmental agencies

at the disposal of a belligerent in such a way as to aid it directly or indirectly in the prosecution

of the war.⁶⁶

Although a neutral State may not supply war-related goods and services to belligerents, a

neutral State is not called upon to prevent the export or transport, on behalf of one or other of the

belligerents, of arms, munitions, or anything that can be of use to an armed force.⁶⁷ Commercial

transactions between belligerent States and neutral corporations, companies, citizens, or persons

resident in a neutral State are not prohibited.⁶⁸ A belligerent State may purchase from such

corporations, companies, citizens, or persons supplies, munitions, or anything that may be of use

to an armed force, which can be exported or transported without involving the neutral State.⁶⁹

acquiescence have reference to neutral obligations to permit belligerent measures of repression against neutral

subjects found rendering certain acts of assistance to an enemy.”).

⁶³ Philander C. Knox, Attorney General, Neutrality—Military Supplies—Horses, Apr. 4, 1902, 24 OPINIONS OF THE

ATTORNEY GENERAL 15, 18 (1903) (“One of the rules of international law which seems to be now fully agreed upon

is that a neutral nation shall not give aid to one of the belligerents in the carrying on of the war.”).

⁶⁴ HAGUE XIII art. 6 (“The supply, in any manner, directly or indirectly, by a neutral Power to a belligerent Power,

of war-ships, ammunition, or war material of any kind whatever, is forbidden.”).

⁶⁵ 1928 PAN AMERICAN NEUTRALITY CONVENTION art. 16 (“The neutral state is forbidden: a) To deliver to the

belligerent, directly or indirectly, or for any reason whatever, ships of war, munitions or any other war material; b)

To grant it loans, or to open credits for it during the duration of war. Credits that a neutral state may give to

facilitate the sale or exportation of its food products and raw materials are not included in this prohibition.”).

⁶⁶ TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 208 (“As Hyde has observed, ‘the duty to abstain from

giving aid is a broad one and covers a vast field of governmental activities;’ for in addition to the prohibition against

supplying belligerents with war materials of any kind the neutral is obligated, in general, ‘to abstain from placing its

various governmental agencies at the disposal of a belligerent in such a way as to aid it directly or indirectly in the

prosecution of the war.’ Thus in naval warfare, the public vessels of a neutral state must refrain from rendering

services of any kind to belligerent naval units at sea.”).

⁶⁷ 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art. 22 (“Neutral states are not obligated to prevent

the export or transit at the expense of any one of the belligerents of arms, munitions and in general of anything

which may be useful to their military forces.”); HAGUE V art. 7 (“A neutral Power is not called upon to prevent the

export or transport, on behalf of one or other of the belligerents, of arms, munitions of war, or, in general, of

anything which can be of use to an army or a fleet.”); HAGUE XIII art. 7 (“A neutral Power is not bound to prevent

the export or transit, for the use of either belligerent, of arms, ammunitions, or, in general, of anything which could

be of use to an army or fleet.”).

⁶⁸ 1956 FM 27-10 (Change No. 1 1976) ¶527 (“Commercial transactions with belligerents by neutral corporations,

companies, citizens, or persons resident in neutral territory are not prohibited.”); 1928 PAN AMERICAN MARITIME

NEUTRALITY CONVENTION art. 15 (“Of the acts of assistance coming from the neutral states, and the acts of

commerce on the part of individuals, only the first are contrary to neutrality.”).

⁶⁹ 1956 FM 27-10 (Change No. 1 1976) ¶527 (“A belligerent may purchase from such persons supplies, munitions,

or anything that may be of use to an army or fleet, which can be exported or transported without involving the

neutral State.”).

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The supply of services and goods to a belligerent State, however, must not convert neutral

territory into a base of operations.⁷⁰

If a neutral State prohibits the export or transport of arms, munitions, or anything that can

be of use to an armed force, every measure of restriction or prohibition taken by a neutral State

in regard to the provision of such supplies or munitions must be impartially applied by it to all

belligerent States.⁷¹

15.3.2.2 Duty to Prevent Violations of Neutrality Within Its Jurisdiction. A

neutral State has certain obligations to prevent violations of its neutrality within its territory. A

neutral State has an obligation to prevent violations of its neutrality committed by belligerent

forces.⁷² A neutral State also has an obligation to prevent violations of its neutrality committed

by persons within its jurisdiction.⁷³

15.3.2.3 Public Expressions of Sympathy Are Not Violations of Neutrality. Public

expressions of sympathy for one belligerent or disapproval of another belligerent are not

violations of duties of neutrality.⁷⁴

15.3.2.4 Authorized Humanitarian Assistance Is Not a Violation of Neutrality.

Humanitarian assistance given in accordance with international law is also not a violation of

duties of neutrality.⁷⁵ For example, a neutral State’s performing of the role of the Protecting

Power in accordance with the 1949 Geneva Conventions is not regarded as unneutral conduct.⁷⁶

⁷⁰ Refer to § 15.5.1 (Prohibition on Outfitting Hostile Expeditions With Supplies and Services for a Belligerent From

Neutral Territory).

⁷¹ HAGUE V art. 9 (“Every measure of restriction or prohibition taken by a neutral Power in regard to the matters

referred to in Articles 7 and 8 must be impartially applied by it to both belligerents.”).

⁷² HAGUE XIII art. 25 (“A neutral Power is bound to exercise such surveillance as the means at its disposal allow to

prevent any violation of the provisions of the above Articles occurring in its ports or roadsteads or in its waters.”);

HAGUE V art. 5 (“A neutral Power must not allow any of the acts referred to in Articles 2 to 4 to occur on its

territory. It is not called upon to punish acts in violation of its neutrality unless the said acts have been committed

on its own territory.”).

⁷³ See, e.g., Consultative Meeting of Foreign Ministers of the American Republics, Final Act of the Meeting: V

General Declaration of Neutrality of the American Republics, ¶3, Oct. 3, 1939, 1 DEPARTMENT OF STATE BULLETIN

326, 327 (Oct. 7, 1939) (The American Republics resolve “[t]o declare that with regard to their status as neutrals,

there exist certain standards recognized by the American Republics applicable in these circumstances and that in

accordance with them they: ... (b) Shall prevent, in accordance with their internal legislations, the inhabitants of their

territories from engaging in activities capable of affecting the neutral status of the American Republics.”); Treaty

between the United States and Great Britain, art. 6, May 8, 1871, 17 STAT. 863, 865 (“A neutral Government is

bound - … Thirdly, to exercise due diligence in its own ports and waters, and, as to all persons within its

jurisdiction, to prevent any violation of the foregoing obligations and duties.”).

⁷⁴ LAUTERPACHT, II OPPENHEIM’S INTERNATIONAL LAW 655 (§294) (“The required attitude of impartiality is not

incompatible with sympathy with one belligerent, and disapproval of the other, so long as these feelings do not find

expression in actions violating impartiality. Thus, not only public opinion and the press of a neutral State, but also

its Government, may show their sympathy to one party or another without violating neutrality.”).

⁷⁵ LAUTERPACHT, II OPPENHEIM’S INTERNATIONAL LAW 655 (§294) (“Moreover, acts of humanity on the part of

neutrals and their subjects, such as the sending to military hospitals of doctors, medicine, provisions, dressing

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