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Part V Revival of Classical Concepts?, Ch.43 Blockades and Interdictions

Wolff Heintschel von Heinegg

From: The Oxford Handbook of the Use of Force in International Law

Edited By: Marc Weller

From: Oxford Public International Law (http://opil.ouplaw.com). (c) Oxford University Press, 2021. All Rights Reserved. Subscriber: null; date: 18 January 2021

Subject(s):
UN Charter — Specific treaties — State practice — Opinio juris — Customary international law — Evidence — Admissibility of evidence — Flag state — Territorial sea — UNCLOS (UN Convention on the Law of the Sea) — Coastal states — Hot pursuit

(p. 925) Chapter 43  Blockades and Interdictions

I.  Introduction

Stating that blockades and interdictions are a ‘revival of classic concepts’ seems to suggest that the concepts, while certainly valid in a distant past, are no longer compatible with the current international legal regime governing the use of force or contemporary public international law in general. Indeed, one might argue that international navigation and aviation may not be interfered with, unless the UN Security Council has expressly authorized such interference or if it is necessary for self-defence purposes.

The mere characterization of a concept as ‘classic’ does not mean it has fallen into desuetude. This certainly holds true for blockades, interdictions, and other methods by which states interfere with international navigation and aviation. On the one hand, blockade is expressly referred to in Article 42 of the UN Charter and, according to a long-standing treaty,1 military manuals,2 and other (p. 926) documents3 continues to be a recognized method of naval and aerial warfare. On the other hand, the practice of the UN Security Council,4 state practice,5 and the progressive development of international treaty law6 provide sufficient evidence of the legality of interdiction operations if they serve a recognized purpose. This does not mean that states are at an almost unlimited liberty. Rather, the principle of flag state sovereignty and the freedom of navigation and aviation—either for economic, or for security policy, reasons—continue to be of overall importance. Therefore, states agree that interdiction operations taken against foreign vessels and aircraft would constitute a violation of the exclusive jurisdiction and sovereignty of the flag state or state of registry, if there is no valid legal basis or the operations do not remain within the rather strict limits of the applicable rules and principles of international law.7

The purpose of the present chapter is to identify those rules and principles that allow for a naval or aerial blockade or some other form of interference with foreign vessels and aircraft, without the explicit authorization by the UN Security Council. It may be added in this context that an authorization by the Security Council, although highly desirable, will in most cases not serve as a perfect legal basis. Even if the Council authorizes the use of ‘all necessary means’ or the use of force in order to enforce an embargo,8 for instance, there will be numerous unresolved legal issues with regard to the status of persons and objects, the scope of lawful enforcement measures, and the relevance of other branches of international law, such as human rights.9

(p. 927) While the focus will be on the jus ad bellum, the jus in bello will also be taken into consideration in order to clarify the concept of blockade. Moreover, some states parties to a non-international armed conflict or to an armed conflict whose classification is contested have interfered with foreign vessels and aircraft and have justified their measures by reference to the jus in bello.

II.  Blockade Under the Jus ad Bellum and the Jus in Bello

A.  Concept and Distinction

The term ‘blockade’ is all too often used for measures that do not qualify as a blockade proper, such as sieges on land or the barring of passage through an international strait or an international canal.10 Sometimes the use of the term is cautiously avoided because states are unwilling to admit that they are indeed establishing and enforcing a blockade against another state.11 Neither the erroneous use of the term nor the refusal of its use are relevant to the legal concept of blockade. A blockade is a military operation to prevent all vessels and/or aircraft from entering or exiting specified ports, airports, or coastal areas belonging to or under the control of another state.12 Hence, a blockade by its very nature can only be established off the coast of another state and not within the territory of another state or within a sea area that is not geographically connected with land territory, that is, on the high seas. A blockade will regularly affect freedom of navigation and aviation in (p. 928) sea areas and beyond the outer limit of the territorial sea and in the airspace above. A blockade must be distinguished from other measures interfering with navigation or aviation, such as contraband control, exclusion or no-fly zones, naval minefields, embargoes, or maritime interdiction operations.13

B.  Conditions of Legality

The maintenance and enforcement of a blockade is achieved by the use of the armed forces and, if necessary, by the use of military force against vessels and/or aircraft breaching, or attempting to breach, the blockade. While it may be doubtful whether and to what extent the use of force against merchant vessels and civil aircraft is to be measured in the light of Article 2(4) of the UN Charter,14 the establishment and maintenance of a blockade by the use of armed forces qualifies as an act of aggression15 and, a fortiori, use of force prohibited under that provision, unless justified by another rule of international law.

There seems to be general agreement among states and international lawyers on the legality of a naval or aerial blockade during an international armed conflict.16 In view of the principle of equal application of the jus in bello, it is irrelevant whether one of the parties to the conflict has resorted to the use of force in violation of the jus ad bellum or whether the establishment of the blockade as such constitutes a prohibited use of force under Article 2(4) of the UN Charter.17 Namely, the illegality or legality under jus ad bellum has no impact on the illegality or legality under the jus in bello. The efforts to limit the in bello legality in the light of the jus ad bellum 18 have been futile and cannot be considered as reflecting the general consensus of (p. 929) states. Hence, if, during an international armed conflict, a blockade is in compliance with the rules and principles of the law of air or naval warfare,19 its legality may not be doubted. This is without prejudice to the powers of the UN Security Council to determine a wide-ranging obligation of the aggressor state, under the jus ad bellum, to compensate all losses suffered by other states and by individuals during the armed conflict.20

Finally, the international law of the sea does not restrict the exercise of belligerent rights at sea. According to the third sentence of the first paragraph of Article 87 of the 1982 UN Convention on the Law of the Sea (UNCLOS),21 inter alia, the list of high seas freedoms in list a)–f) is not exhaustive. Accordingly, the freedom of the high seas also comprises other uses. Moreover, it is emphasized in the second sentence of Article 87(1) of UNCLOS that the freedom of the high seas is to be exercised not only ‘under the conditions laid down by this Convention’ but also ‘by other rules of international law’. Hence, the admissibility and legality of military uses follows from either the law of naval warfare and neutrality at sea22 or from other rules and principles of customary international law.23

C.  Blockade Authorized as a Military Enforcement Measure

Article 42 of the UN Charter provides, inter alia, that the UN Security Council may decide on the establishment and enforcement of a blockade as a military enforcement measure. Nowadays, it is undisputed that the Council is entitled to authorize states to take such measures, by either specifically referring to blockade or by merely authorizing the use of ‘all necessary means’.24 Then, an individual state or a (p. 930) coalition of states would be provided with a sufficient legal basis for the establishment and enforcement25 of an aerial and/or naval blockade.

In such instances, the armed forces of member states wishing to make use of the authorization will regularly not be UN personnel, as defined in the 1994 Convention on the Safety of United Nations and Associated Personnel.26 The question thus arises whether and to what extent the law of blockade, as part of the jus in bello, governs the respective blockade. It would not suffice to merely refer to the national, that is, non-UN, status of the armed forces or to the existence of an international armed conflict and to apply the respective rules in an unmodified manner, if the Security Council has not expressly provided for exceptions.

On the one hand, there is no room for the traditional rules of neutrality if the Security Council has taken action under Chapter VII of the Charter.27 Therefore, states not actively taking part in the enforcement measures cannot rely on their impartial stance and claim to remain unmolested by the measures taken. Rather, they are obliged to refrain from any activities that could jeopardize the effectiveness of such measures. On the other hand, the unmodified application of the jus in bello rules on blockade would jeopardize the very object and purpose of enforcement measures under Chapter VII—maintaining or restoring international peace and security. Therefore it is not possible to consider a blockade authorized by the Security Council void because it no longer complies with the principle of effectiveness. It must be stressed, however, that the principle of humanity and the ensuing obligations of the blockading power with a view to protecting the civilian population in the blockaded area continue to apply.28

D.  Contested or Unresolved Legal Issues

While the foregoing findings most likely reflect the general consensus of states, there are some unresolved or even contested issues regarding the legality of blockades.

1.  Blockades in situations other than international armed conflict

A highly contested issue relates to blockades established and enforced in situations not amounting to an international armed conflict. In this context it is important to distinguish two situations.

(p. 931) The first relates to the establishment of a blockade on the basis of the right of self-defence in response to an imminent armed attack by another state. In principle, the mere fact that a state exercises the right of self-defence by resorting to the use of armed force does not in and of itself bring into existence an international armed conflict.29 However, if it is agreed that the law of international armed conflict becomes applicable ‘whenever there is a resort to armed force between States’30 it would be rather difficult to deny the existence of an international armed conflict if a state responds to an imminent armed attack by establishing a blockade against another state. However, if there existed no international armed conflict, the measures taken would have to comply with the recognized limitations, that is, necessity, proportionality, and imminence.31 Measures aimed at preventing exit and entry of foreign neutral vessels and/or aircraft would be lawful under the right of self-defence in exceptional circumstances only because there would have to be a clear nexus to the armed attack. Enforcement measures taken against all vessels, that is, regardless of such a nexus, would most probably be contrary to the principles of necessity and proportionality. The state exercising the right of self-defence would be obliged to allow vessels that cannot be associated with the self-defence situation to leave or enter the coastal area in question. The measure in question would thus no longer qualify as a blockade but would have to be characterized as some form of interdiction operation.

The second situation relates to blockades established in the course of a non-international armed conflict. While there is general agreement that non-states parties to such a conflict are not entitled to make use of that method of warfare, it is less clear whether states parties would have the right to establish and enforce a blockade that is primarily directed against their opponent. According to the position taken here, there is no doubt that states are entitled to close parts of their territorial sea to foreign ships as long as the relevant provisions of the law of the sea are observed.32 Entry into national airspace has always been dependent upon prior approval by the authorities of the state. If such conduct is admissible in peacetime it is, a fortiori, lawful in a situation of non-international armed conflict, which constitutes a threat to the security of the state. However, the measures taken must be strictly limited to the territorial sea and, to the extent Article 33 of UNCLOS is observed, the contiguous zone. Then, the closure of parts of a state’s territorial sea no longer qualifies as (p. 932) a blockade. In sum, ‘there is no consistent state practice and opinio juris suggesting blockade is available outside an [international armed conflict]’.33

Whether the establishment of a blockade is lawful in a non-international armed conflict is an issue that arose in the context of Israel’s blockade of the Gaza Strip and its measures against the so-called Gaza Flotilla in 2010.34 Those who considered Israel’s blockade as contrary to international law argue, inter alia, that the conflict was non-international in character.35 There are convincing arguments either in favour of the international character of the conflict or of the applicability of the law of international armed conflict and, thus, of the law of blockade.36 If the law of international armed conflict was applicable to the Gaza blockade, neutral vessels and aircraft were obliged to respect the blockade and to comply with all legitimate orders by the blockade force.37 Forcible resistance is considered an ‘act of hostility’ that renders the vessel or aircraft liable to attack.38

2.  Proportionality and humanity

If a blockade constitutes a method of warfare, there is, in principle, no room for applying a general principle of proportionality. Rather, proportionality is to be assessed in the light of the jus in bello, that is, of the prohibition of excessive civilian casualties in relation to the military advantage anticipated and of starvation as a method of warfare.39 The mere fact that a blockade has a negative impact on the supply of the civilian population in the blockaded area does not render a blockade unlawful. Of course, the blockading power is obliged to provide for relief consignments, if the civilian population of the blockaded area is no longer adequately provided with goods essential for its survival, that is, with food, water, and medical supplies.40 It is, however, contested whether the facts on the ground justify the (p. 933) conclusion that the civilian population is in fact no longer supplied with goods essential for its survival or that the civilian casualties are excessive in relation to the military advantage anticipated.41

It would fall short of the applicable law if the general principle of proportionality were disregarded altogether. Vessels and aircraft breaching or attempting to breach a blockade are liable to capture, not to attack.42 They only lose their protection against attack if they effectively contribute to the enemy’s military action or if they are actively resisting interception and capture.43 Hence, the mere fact that vessels or aircraft endeavour to escape interception or capture does not mean that they may be sunk or shot down on sight. However, the blockading force may use all proportionate measures, including the use of force, with a view to stop a vessel or to force an aircraft to land on a designated airfield.44 The permissible use of force may range from warning shots to disabling fire but must at all times be proportionate.

The same standards apply to measures taken against passengers and crew who actively resist enforcement measures taken by the blockade forces.45 Again, as shown in the case of the Gaza blockade, establishing and analysing the facts in the light of proportionality is a most difficult undertaking and will only in exceptional cases result in a generally accepted legal evaluation.46

E.  Further Observations on Blockade

The establishment, maintenance, and enforcement of a naval and/or aerial blockade are highly challenging tasks for the blockading power. In view of the principle of effectiveness there must be a high probability that vessels and/or aircraft are in fact prevented from entering or exiting the blockaded area. This presupposes that the blockading power exercises a considerable degree of superiority and that it applies the blockade in a strictly impartial manner. If those conditions are met, the blockading power is entitled to interfere not only with enemy but also with neutral (p. 934) navigation and aviation. It may be added that blockade is the only method of warfare by which a belligerent is entitled to prevent the exports of goods from enemy territory.

By its very nature, a blockade will very often have far-reaching effects on maritime and air traffic. Naturally, neutral states will not easily be prepared to accept belligerent measures interfering with their vessels and aircraft. The history of blockade gives ample examples of protests and other measures by which neutral states have doubted the legality of blockades as such or of enforcement measures taken by the blockading power.47 It is, however, most doubtful whether such statements and measures may be understood as expressions of opinio juris. All too often, they have been merely political in character or guided by extralegal considerations. Under the law of blockade that is limited to situations of international armed conflict,48 neutral states are obliged to tolerate interference with their shipping and aviation if the blockade is in compliance with the applicable jus in bello. If a neutral state decides to prevent the blockading power from exercising its rights, it either violates its obligations under the law of neutrality or it becomes a party to the conflict.

III.  Interdiction Operations

Whereas blockade is a well-established legal concept, ‘interdiction operations’ is an operational term of art used for describing a variety of measures. Those measures have in common that, although to a varying degree, they have an impact on the freedom of navigation and/or overflight enjoyed by foreign aircraft and vessels. Moreover, they serve a common purpose insofar as they are to protect security interests either of individual states or of the international community. These common features may not distract from the fact that there are several distinct legal bases for interdiction operations. Those legal bases are exceptional in character insofar as they allow interference with foreign vessels and aircraft that, in principle, constitutes an infringement of the sovereignty of the flag state or the state of (p. 935) registry.49 Hence, the legality of interdiction operations is subject to considerable legal limitations.

If interdictions operations are based on a decision taken by the UN Security Council under Chapter VII, their legality cannot be doubted.50 Although the respective resolutions often lack the necessary clarity as to the concrete measures that are permissible under their terms,51 interdiction operations authorized by the Council are not dealt with in the present chapter. Likewise, counter-piracy52 and counter-proliferation53 operations are not addressed because they are covered by other contributions of this volume.54 Finally, measures against foreign aircraft and vessels taken during an international armed conflict, which are governed by the law of prize as part of the jus in bello 55 and not by the jus ad bellum cannot be addressed either.

A.  Scope of Interdiction Operations

In the maritime context,56 interdiction operations ‘may range from querying the master of [a]‌ vessel to stopping, boarding, inspecting, searching, and potentially seizing the cargo or the vessel’.57 Moreover, states may establish zones around units and warn vessels that they could be considered as showing ‘hostile intent’ and that they risk being subjected to certain measures. Such zones may also be established in specified sea areas for various purposes, such as weapons exercises, military (p. 936) manoeuvres, or the protection of ‘high-value targets’.58 In the aerial context, similar measures may be taken with a view to identifying an aircraft’s nationality, course, cargo, or passengers, for instance by intercepting the aircraft and/or ordering it to land at a specified airfield or airport.59 These zones will in most cases also be applied and enforced against aircraft. Finally, states may subject aircraft and vessels to restrictions, in the exercise of their right of self-defence.

If international law provides a legal basis for any such interdiction operations, the aircraft or vessels affected will regularly be obliged to comply with all legitimate orders. If they do not comply, they either operate at their own risk or they may be subjected to measures enforcing the exercise of the right in question. However, whether the right may be enforced by the use of proportionate force depends on the applicable legal basis.

B.  Legal Bases under International Treaties

With regard to maritime interdiction operations (MIO) both UNCLOS and the Suppression of Unlawful Acts (SUA) Convention, as amended by the 2005 Protocol,60 provide the legal bases necessary for an interference with foreign shipping. Further legal bases are provided by special treaties.

1.  UN Convention on the Law of the Sea

The right of coastal states to interfere, within their territorial sea, with foreign vessels is recognized by Articles 25 and 27 of UNCLOS. According to the latter provision the coastal state may exercise its criminal jurisdiction on board a foreign ship, that is, it may arrest persons, conduct investigations, and temporarily capture the vessel, if crimes have been committed on board during passage. However, a breach of the domestic criminal law of the coastal state will justify the exercise of its criminal jurisdiction only in cases where the crime has been committed on board a ship passing through the territorial sea after having left the coastal state’s internal waters (p. 937) (Art 27(2)). If the vessel concerned has not left a port of the coastal state the exercise of criminal jurisdiction, according to Article 27(1), is limited. If the crime giving rise to interdiction measures has been committed before entry into the territorial sea and if the ship, proceeding from a foreign port, is only passing through the territorial sea without entering internal waters, the coastal state may not take any steps on board the ship.61 According to Article 25(1), the coastal state ‘may take the necessary steps in its territorial sea to prevent passage which is not innocent’. According to Article 19(1), passage is not innocent if it is ‘prejudicial to the peace, good order or security of the coastal State’ or if the vessel is engaged in one of the activities listed in Article 19(2).

Coastal states are entitled to take enforcement measures against foreign ships in sea areas beyond the outer limit of the territorial sea, if they have proclaimed a contiguous zone.62 Such measures ‘may be taken only in respect of offences committed within the territory or territorial sea of a State, not in respect of anything done within the contiguous zone itself.’63

Coastal states also enjoy the right of ‘hot pursuit’.64 However, an arrest after hot pursuit is legal only if pursuit has commenced within the sea areas mentioned in Article 111(1) and (2), it has been continuous, and in compliance with the further conditions laid down in that article.

Apart from ‘hot pursuit’, foreign vessels may only be boarded in high seas areas, if ‘there is reasonable ground for suspicion’ that they are engaged in one of the activities enumerated in Article 110(1). According to Article 92(2), vessels flying the ‘flags of two or more States, using them according to convenience,…may be assimilated to a ship without nationality’ and they may be boarded in accordance with Article 110. The right of visit is limited to the verification of ‘the ship’s right to fly its flag’. The intercepting warship or military aircraft may only take those measures that are necessary to verify whether the grounds for suspicion prove to be founded.65 If suspicion remains after the documents have been checked, a further examination on board the ship may ‘be carried out with all possible consideration’.66 Article 110 gives no guidance as to the further measures that may be taken against a vessel if the suspicions prove to be founded. However, the right of visit would be futile if the vessel could not be diverted to a designated port under the command of the boarding team.

Finally, under Article 98, there is a duty to render assistance to all persons who are in distress at sea. Rendering such assistance may imply the necessity to prevent other ships or aircraft from approaching the respective area or from interfering with (p. 938) the rescue operation. If distress arose due to the conduct of a vessel, the only option may be to take measures against the vessel, in order to either prevent or to terminate the conduct.

2.  Convention for the Suppression of Unlawful Acts Against the Safety of Maritime Navigation (SUA Convention) of 1988 (as amended in 2005)

According to the SUA Convention, as amended by the 2005 Protocols, foreign merchant vessels encountered on the high seas may be boarded and searched if there are grounds for suspicion that they are involved in either of the offences specified in Articles 3, 3bis, 3ter, or 3quater, and if the flag state has authorized those measures.67 The necessary consent by the flag states, according to Article 8bis, paragraph 5, may be given in advance and in a general manner. It is important to note that, according to Article 8bis, paragraph 9, the use of force is allowed, ‘when necessary to ensure the safety of its officials and persons on board, or where the officials are obstructed in the execution of the authorized actions.’ However, ‘Any use of force pursuant to this article shall not exceed the minimum degree of force which is necessary and reasonable in the circumstances.’

3.  Other treaties

Flag states and states of registry may always consent to the boarding of their vessels or to the interception of their civil aircraft by special agreement. For instance, such agreements have been concluded by the US and various flag states with a view to preventing the proliferation of weapons of mass destruction by non-state actors.68 Moreover, boarding is permissible under regional treaties concerning the suppression of illicit trafficking of drugs at sea or in the air.69

4.  Enforcing interdiction rights under existing treaties

Apart from the 2005 SUA Convention, as amended in 2005, the treaties referred to earlier do not expressly provide for the use of force if the vessel or aircraft does not comply with the legitimate orders by the warship or military aircraft or if it actively resists visit, boarding, capture, or diversion. According to those treaties, the intercepted vessels and aircraft are obliged to tolerate the exercise of the respective (p. 939) measures. Hence, any act of non-compliance or of active resistance triggers the right of the intercepting warship or military aircraft to resort to the use of force that is strictly necessary to enforce compliance or to overcome resistance. Only that degree of force necessary is permissible to enforce the right in question. It may therefore be in accordance with the law to fire warning shots or to apply other measures that are apt to induce the vessel or aircraft to comply with the respective orders or to desist from further resistance. However, the use of lethal force will be lawful in exceptional cases only and will most probably be limited to situations of self-defence. For instance, if an act of resistance amounts to an imminent armed attack against a boarding team, the use of deadly force, while not permissible under a law enforcement paradigm, would be lawful under the right of self-defence.70

C.  Applicability of Prize Law During Non-International Armed Conflicts?

During an international armed conflict, belligerents are entitled to exercise prize measures, that is, to capture enemy merchant vessels and aircraft and to visit, search, and, if there are reasonable grounds for suspicion that they are engaged in the carriage of contraband, to capture neutral merchant vessels and civil aircraft.71 States parties to a non-international armed conflict sometimes resort to the use of prize measures. It is, however, doubtful whether in the course of a non-international armed conflict foreign vessels and aircraft may be subjected to visit and search under the law of prize.

The government that is confronted with insurgents, rebels, etc is entitled to suspend the right of innocent passage through the territorial sea72 and to prohibit access to the ports controlled by the rebels. Accordingly, it may use all necessary means, including the use of force, in order to prevent such passage or access. However, measures in the sea areas beyond the outer limit of the territorial sea and in the airspace above seem to have no basis in international law.

During the non-international armed conflicts in Spain73, Algeria,74 and Sri Lanka75 the parties took the position that they were entitled to interfere with foreign (p. 940) merchant vessels on the high seas in order to prevent the flow of arms and other materiel to the respective opponent. The reactions by the affected flag states were far from uniform.76 Moreover, even those states that were not prepared to consider the Gaza conflict as an international armed conflict did not protest against Israel’s exercise of the right of visit and search.77

Guilfoyle believes that ‘On the basis of relevant state practice one can at most hazard a suggestion that irrespective of the precise classification of a conflict, states are likely to tolerate the assertion of a blockade only in cases of higher-intensity conflicts on a par with the traditional understanding of war.’78 However, the intensity of a non-international armed conflict is but one indicator for the legality of interdiction operations by the state that is party to a non-international armed conflict. Intensity is not sufficient to justify the applicability of the law of prize that is applicable in international armed conflict only.79

The definition of lawful military objectives applies in non-international armed conflict.80 There is no convincing reason that would justify its limitation to vessels and aircraft of the nationality of the state concerned. Accordingly, any vessel, regardless of the flag it is flying, and any aircraft, wherever registered, used by an organized armed group in the course of a non-international armed conflict for military purposes constitutes a lawful military objective by either nature or use. Hence, the parties to a non-international armed conflict will not refrain from attacking such vessels or aircraft as soon as they have left the territorial sea or the national airspace. It is not to be expected that other states will protest attacks on such vessels and aircraft for the sole reason that such attacks occurred in international sea areas or in international airspace. If such vessels and aircraft may be attacked, it is of course lawful to capture them (and to enforce capture by the use of force).

The intensity of armed hostilities during a non-international armed conflict may, under exceptional circumstances, constitute an element of proof for the necessity of interdiction operations in high seas areas. State practice during non-international armed conflicts seems to justify the conclusion that the state (p. 941) party to a non-international armed conflict—not the non-state actor—is entitled to resort to interdiction operations on the high seas and in international airspace if: (1) vital security interests of the state must be at stake; (2) there are reasonable grounds for suspicion that the foreign vessels and aircraft are engaged in activities jeopardizing those security interests (eg by supplying the non-state party with arms); (3) the measures are taken in close vicinity to the conflict area; and (4) the measures are necessary and proportionate.81 If those conditions are fulfilled, the legal basis for the interdiction operations is not prize law. Rather, the legal basis is to be seen in the right of self-defence or in the customary right of self-preservation in order to protect the territorial and political integrity of the state. The finding by the International Court of Justice that the right of self-defence does not apply if there is no transborder element82 finds no basis in state practice.

D.  Other Legal Bases?

While it is uncontested that consent by the flag state or by the state of registry constitutes a sufficient legal basis for the exercise of interdiction operations against foreign vessels and aircraft, there is less agreement with regard to other legal bases that have been asserted by states and by legal scholars.

1.  Master’s consent

States disagree as to whether the consent of the master suffices to justify the boarding and search of a foreign vessel. Indeed, the flag state principle and the underlying principle of state sovereignty seem to justify the conclusion that, absent express exceptions in international treaty or customary law, the consent of the flag state or state of registry is paramount to the legality of any act of interference. The boarding and searching of foreign vessels and aircraft constitutes an exercise of jurisdiction that by necessity violates the ‘exclusive jurisdiction’83 of the flag state.84 Since the master is not entitled to waive the flag state’s jurisdiction, his consent is legally irrelevant. Some states take the position that master’s consent justifies the exercise of so-called ‘consensual boarding’,85 because the ‘plenary authority of the master over (p. 942) all activities related to the operation of his vessel while in international waters is well established in international law and includes the authority to allow anyone to come aboard his vessel as his guest, including foreign law enforcement officials’.86 However, this does not mean that such consent provides a legal basis for the exercise of maritime enforcement jurisdiction. Although the ‘voluntary consent of the master permits the boarding,…it does not allow the assertion of law enforcement authority. A consensual boarding is not, therefore, an exercise of maritime law enforcement jurisdiction per se.’87 Moreover, it may not be left out of consideration that every ‘consensual boarding’ is ‘subject to conditions imposed by the master and may be terminated by the master at his discretion’.88 Hence, if accepted as a legal basis, a master’s consent will at best serve as a tool for verifying a vessel’s true nature, its cargo, documents, and destination but not for enforcement measures that go beyond such verification.

2.  Right of individual or collective self-defence

It is unclear whether and to what extent the right of individual or collective self-defence provides a basis for interdiction operations. Of course, in the case of an imminent armed attack the victim state is entitled to take all necessary and proportionate measures in order to eliminate the self-defence situation. If and insofar as foreign vessels and aircraft by their conduct directly contribute to the imminent armed attack, they may be made the objects of self-defence measures, including interdiction operations. The same holds true if there are reasonable grounds for suspicion that the vessels and aircraft are used in support of the imminent armed attack. Then, however, the exercise of the right of self-defence is limited to what is strictly necessary and proportionate and will only in exceptional circumstances justify the use of deadly force.89

According to the position taken here, the interdiction operations conducted by the US in the Persian Gulf were therefore not justified because of the rather vague wording of Security Council Resolution 661 (1990),90 as submitted by Zeigler,91 but rather because they were taken in response to the illegal attack by Iraq against Kuwait. It may be recalled that Security Council Resolution 661 (1990) called for the embargo of trade to and from Iraq and Kuwait, but did not specifically authorize interdiction operations.92 Still, between 16 August and 25 August 1990 the US conducted such operations.93 Contrary to the argument of Zeigler, a resolution (p. 943) only serves as a legal basis for such operations if the UN Security Council either expressly authorizes member states to that effect, as it did in Resolution 665 (1990), or if it uses the phrase ‘all necessary means’. If the resolution only obliges member states to comply with an embargo, this as such does not imply the authorization of enforcement measures against foreign vessels and aircraft. It must be borne in mind that, in 1991, the use of force against Iraq did not necessarily constitute a military enforcement measure under Chapter VII of the Charter. Rather Security Council Resolution 678 (1990)94 was an endorsement of the exercise of the right of collective self-defence. None of the resolutions adopted by the Security Council can be interpreted as limiting the exercise of the right of self-defence. Hence, the states cooperating with Kuwait were entitled to autonomously decide upon the point in time at which to exercise the right of collective self-defence.

Another problem with regard to the right of self-defence relates to interdiction operations within the framework of counterterrorism operations. For instance, states contributing to Operation Enduring Freedom based the right of visit either on the jus in bello, flag state consent, or the right of self-defence.95 Operation Active Endeavour was based on Article V of the Washington Treaty but the measures taken were limited to ‘compliant boardings’.96 Obviously, none of the states claimed the right to undertake other interdiction operations. It is interesting that the right of self-defence continues to serve as a legal basis for those counterterrorism operations although states do not seem to be prepared to specify the exact nature and scope of measures they consider a lawful exercise of the right of self-defence with regard to maritime interdiction operations. This lack of clarity is certainly an obstacle to the development of a distinct legal regime applicable to interdiction operations. Moreover, it leaves the armed forces entrusted with counterterrorism operations in a legal grey area that will prevent them from taking the measures necessary to effectively eliminate the threat posed by transnational terrorism.

3.  Zones

The ‘appropriate measures’ taken within safety zones provided for in Article 60(4) of UNCLOS might be considered a form of maritime interdiction operation. In view of their limited extent of 500 metres they do not pose a noteworthy obstacle to international shipping and can therefore be ignored here.

However, warning zones may have an impact on the exercise of the freedoms of navigation and overflight. Such warning zones may be established around naval units operating in an uncertain operating environment. Their object is:

to help sort the common operational picture and ascertain the intent of inbound entities. This objective may be accomplished during peacetime while adhering to international law (p. 944) as long as the navigational rights of other ships, submarines, and aircraft are respected. Specifically, when operating in international waters, commanders may assert notice (via NOTAMs [Notices to Airmen] and NOTMARs [Notices to Mariners]) that within a certain geographic area, for a certain period of time, dangerous military activities will be taking place. Commanders may request that entities traversing the area communicate with them and state their intentions. Moreover, such notice may include reference to the fact that if ships and aircraft traversing the area are deemed to represent an imminent threat to U.S. naval forces they may be subject to proportionate measures in self-defense. Ships and aircraft are not required to remain outside such zones and force may not be used against such entities merely because they entered the zone. Commanders may use force against such entities only to defend against a hostile act or demonstrated hostile intent, including interference with declared military activities.97

Hence, warning zones are a tool used for force protection purposes and should not be considered as a type of maritime interdiction operation.

Other zones, especially ‘exclusion zones’, may not be made use of in peacetime,98 unless they are strictly necessary and proportionate for self-defence purposes. However, this will be the case in rather exceptional circumstances only.99

4.  Countermeasures

If it is accepted that the UN Security Council may impose, in a general and abstract manner, obligations upon states with regard to, for instance, the suppression of transnational terrorism100 or the proliferation of weapons of mass destruction, including their delivery systems,101 states not complying with the terms of such resolutions commit an internationally wrongful act. According to the position taken here, those states that are specially affected by the internationally wrongful act are entitled to take countermeasures.102 Such countermeasures may include the exercise of interdiction operations against the vessels flying the flag, or against aircraft registered in, the state that is in violation of its obligations under the respective resolution, if there are reasonable grounds for suspicion that the aircraft or vessels are engaged in prohibited activities.103 It will have to be seen whether states are (p. 945) prepared to make use of that justification and to ground interdiction operations on that legal basis.

IV.  Concluding Remarks

According to well-established rules of the jus in bello, a naval or aerial blockade is a lawful method of warfare aimed at preventing all vessels and/or aircraft from entering or leaving the blockaded enemy port, airfield, or coastline. While the circumstances prevailing at the time may cast doubts on the legality of measures enforcing a blockade with regard to the principles of humanity and proportionality, there seems to be general agreement that the parties to an international armed conflict are entitled to make use of blockade and thus interfere considerably with the shipping and aviation of neutral states. According to the position taken here, blockade is a method of warfare that may not be applied in non-international armed conflicts. States parties to such conflict may impose those restrictions that are in accordance with general international law, especially with the law of the sea. However, those measures do not qualify as blockades proper.

If the UN Security Council, acting under Chapter VII, authorizes the establishment and enforcement of a naval or aerial blockade, the states making use of such authorization are not bound by the strict conditions of the traditional law of blockade.

The legal assessment is less clear when it comes to interdiction operations. Security Council resolutions authorizing interdiction operations are all too often vague and do not provide a satisfactory legal basis, especially with regard to the status of persons and objects and the scope of measures that may be taken. The same holds true with regard to the legal bases in international treaties and customary international law. Either they lack the necessary legal clarity or there is no sufficient agreement on their scope. Although states increasingly entrust their armed forces with the exercise of interdiction operations on the high seas or in international airspace, they seem to be unwilling to provide them with legal tools that are operable, specific, and, what is more important, based on a sufficient international consensus. Moreover, the various rules of international treaty and customary law that either directly or indirectly have an impact on the legality of interdiction operations are not applied in the necessary comprehensive manner. Hence, the law may be progressively developed in one area of international law without the other relevant areas of international law being duly taken into consideration. It is therefore (p. 946) important that states willing to take part in interdiction operations take a concerted approach with a view to identifying the legal issues involved and to arrive at a consented legal regime applicable to interdiction operations. However, in view of the vital importance of the freedoms of navigation and overflight, such efforts should not be too proactive and should not focus on current security interests thus ignoring the mid-term and long-term effects.

Footnotes:

Declaration Respecting Maritime Law, Paris, 30 Mar 1856.

The Commander’s Handbook on the Law of Naval Operations (Newport, RI: US Naval War College, 2007), NWP 1-14M, para 7.7; Federal Ministry of Defence of the Federal Republic of Germany, Humanitarian Law in Armed Conflicts—Manual (Bonn: Federal Ministry of Defence of the Federal Republic of Germany, 1992), paras 1051–3; UK Ministry of Defence, The Manual of the Law of Armed Conflict (Oxford: Oxford University Press, 2004), paras 13.65–13.76.

Louise Doswald-Beck (ed), San Remo Manual on International Law Applicable to Armed Conflicts at Sea (Cambridge: Cambridge University Press, 1995), paras 93–104; Harvard Program on Humanitarian Policy and Conflict Research (HPCR), Manual on International Law Applicable to Air and Missile Warfare (Cambridge, MA: HPCR, 2009), Section V; International Law Association, ‘Helsinki Principles on the Law of Maritime Neutrality’, Report of the 68th Conference, Taipei, 1998, para 5.2.10.

See the references in n 8.

eg the counterterrorism operations Operation Enduring Freedom and Operation Active Endeavour, and the operations of states relying on an authorization by the UN Security Council resolutions referred to in n 8.

See eg Art 8bis of the Protocol of 2005 to the Convention for the Suppression of Unlawful Acts Against the Safety of Maritime Navigation, London, 14 Oct 2005, IMO Doc LEG/CONF. 15/21.

See Anglo-American claims Commission, Award, The Jessie, The Thomas F. Bayard and The Pescawha (1926) Nielsen’s Report 479 ff: ‘[It] is a fundamental principle of international maritime law that, except by special convention or in time of war, interference by a cruiser with a foreign vessel pursuing a lawful avocation on the high seas is unwarranted and illegal and constitutes a violation of the sovereignty of the country whose flag the vessel flies.’

See SC Res 221, 9 Apr 1966 (Rhodesia); SC Res 665, 25 Aug 1990 (Iraq); SC Res 875, 16 Oct 1993 (Haiti); SC Res 713, 25 Sept 1991; SC Res 757, 30 May 1992; SC Res 787, 16 Nov 1992; SC Res 820, 17 Apr 1993 (Former Yugoslavia); SC Res 1701, 11 Aug 2006 (UNIFIL); SC Res 1970, 26 Feb 2011; SC Res 1973, 17 Mar 2011 (Libya).

See Martin D. Fink, ‘The Right of Visit for Warships: Some Challenges in Applying the Law of Maritime Interdiction on the High Seas’ (2010) 49 The Military Law and the Law of War Review 7–45. Further Lois E. Fielding, Maritime Interception and U.N. Sanctions (San Francisco, CA: Austin & Winfield, 1997).

10  Egypt’s closure of the Suez Canal in 1956 did not qualify as a blockade stricto sensu. Findings to the contrary are not based upon the law of blockade but upon the prohibition, under Art 1 of the 1888 Convention of Constantinople, to ‘subject the Canal to the exercise of the right of blockade’. Only if that distinction is observed is it correct to state that Egypt had ‘subjected the Canal to a blockade against Israeli ships within the meaning of…Article 1 of the Constantinople Convention’ because the ‘normal meaning of blockade would, in any event, not make much sense in connection with that clause’; Leo Gross, ‘Passage Through the Suez Canal of Israeli-Bound Cargo and Israel Ships’ (1957) 51 American Journal of International Law 530, 541.

11  The most prominent case in the post-1945 era was the ‘Cuban Quarantine’—a term invented to distract from the fact that a blockade proper had been established around Cuba. See, inter alia, Carl Q. Christol and Charles R. Davies, ‘Maritime Quarantine: The Naval Interdiction of Offensive Weapons and Associated Matériel to Cuba, 1962’ (1963) 57 American Journal of International Law 525; Quincy Wright, ‘The Cuban Quarantine’, ibid, 546; Charles G. Fenwick, ‘The Quarantine Against Cuba: Legal or Illegal?’, ibid, 587; Myres S. McDougal, ‘The Soviet-Cuban Quarantine and Self-Defense’, ibid, 597.

12  See, inter alia, Wolff Heintschel von Heinegg, ‘Blockade’ in Rüdiger Wolfrum (ed), Max Planck Encyclopedia of Public International Law (Oxford: Oxford University Press, 2012), vol I, 960, 960.

13  Heintschel von Heinegg, ‘Blockade’ in Wolfrum, Max Planck Encyclopedia of Public International Law, 960.

14  While some states are prepared to resort to the right of self-defence if a merchant vessel flying its flag has been attacked, other states do not share that position. Under the Definition of Aggression (Annex to GA Res 3314 [XXIX] of 14 Dec 1974) an attack on an individual merchant vessel does not constitute an ‘act of aggression’.

15  GA Res 3314, Art 3(c).

16  See the references in nn 2 and 3. Further Robert W. Tucker, The Law of War and Neutrality at Sea (Washington DC: US Government Printing Office, 1957), 283; C. John Colombos, International Law of the Sea (6th rev edn, London: McKay Co., 1967), 714; Lance Edwin Davis and Stanley L. Engerman, Naval Blockades in Peace and War: An Economic History Since 1750 (Cambridge: Cambridge University Press, 2006); Bruce A. Elleman and S. C. M. Paine, Naval Blockades and Seapower. Strategies and Counter-Strategies, 1805–2005 (London: Routledge, 2006).

17  See Henri Meyrowitz, Le principe de l’égalité des belligérants devant la droit de la guerre (Paris: Pedone, 1970); Yoram Dinstein, The Conduct of Hostilities under the Law of International Armed Conflict (2nd edn, Cambridge: Cambridge University Press, 2010), 3.

18  For a critical analysis of the approach by the UK, see Wolff Heintschel von Heinegg, ‘Manoeuvring in Rough Waters: The UK Manual of the Law of Armed Conflict and the Law of Naval Warfare’ in A. Fischer-Lescano et al, Frieden in Freiheit. Peace in Liberty. Paix en liberté, Festschrift für Michael Bothe zum 70. Geburtstag (Baden-Baden: Nomos, 2008), 428, 429 ff.

19  See San Remo Manual, paras 93–104; HPCR Manual, Section V.

20  See SC Res 687 of 3 April 1991, para 16, in which the Security Council, inter alia, reaffirmed that ‘Iraq…is liable under international law for any direct loss, damage—including environmental damage and the depletion of natural resources—or injury to foreign Governments, nationals or corporations as a result of its unlawful invasion and occupation of Kuwait’.

21  A/CONF.62/121 (10 Dec 1982); 1833 UNTS 396.

22  For an analysis of that law, see George P. Politakis, Modern Aspects of the Laws of Naval Warfare and Maritime Neutrality (London: Kegan Paul, 1998); Wolff Heintschel von Heinegg, Seekriegsrecht und Neutralität im Seekrieg (Berlin: Duncker & Humblot, 1995).

23  Hence, it is made clear in the commentary to the ILA Helsinki Principles (at 498) that ‘Although UNCLOS does not explicitly address questions arising out of wartime situations, its clauses on “other rules of international law” (e.g., Article 87, para. 1) include the law of armed conflict.’

24  Jochen A. Frowein and Nico Krisch, ‘Article 42’ in Bruno Simma et al (eds), The Charter of the United Nations: A Commentary (2nd edn, Oxford: Oxford University Press, 2002), vol I, paras 20 ff. On the possible limits of an authorization, see Erika de Wet, The Chapter VII Powers of the United Nations Security Council (Oxford: Hart, 2004), 256 ff.

25  With regard to the admissibility of the use of force, see Rob McLaughlin, ‘The Legal Regime Applicable to Use of Lethal Force When Operating Under a United Nations Security Council Chapter VII Mandate Authorizing “All Necessary Means”’ (2007) 12 Journal of Conflict and Security Law 389.

26  Convention on the Safety of United Nations and Associated Personnel, Art 1(a), A749/49 (1994).

27  See only San Remo Manual, paras 7–9; HPCR Manual, Rule 165.

28  The practice of the Security Council provides sufficient evidence that humanitarian considerations have an impact on the scope of measures taken under Chapter VII of the Charter. See, inter alia, SC Res 661 of 6 August 1990. Further Heintschel von Heinegg, ‘Blockade’ in Wolfrum, Max Planck Encyclopedia of Public International Law, 973.

29  See, inter alia, Terry D. Gill, The 11th of September and the International Law of Military Operations (Amsterdam: Vossiuspers, 2002), 22.

30  International Criminal Tribunal for the Former Yugoslavia, Prosecutor v. Tadić, Decision on the Defence Motion for Interlocutory Appeal on Jurisdiction of 2 Oct 1995, IT-94-1-AR72, para 70.

31  Yoram Dinstein, War, Aggression and Self-Defence (5th edn, Cambridge: Cambridge University Press, 2011), 230 ff.

32  See esp UNCLOS, Art 25(3). On the wide margin of discretion enjoyed by the coastal states, see Robin R. Churchill and Vaughan Lowe, The Law of the Sea (3rd edn, Manchester: Manchester University Press, 1999), 87 ff.

33  Douglas Guilfoyle, ‘The Mavi Marmara Incident and Blockade in Armed Conflict’ (2011) 81 British Yearbook of International Law 171, 217.

34  For the facts, see Report of the Secretary-General’s Panel of Inquiry on the 31 May 2010 Flotilla Incident, paras 83 ff (Sept 2011) (the ‘Palmer Report’).

35  Guilfoyle, ‘The Mavi Marmara Incident and Blockade in Armed Conflict’, 176 ff; Andrew Sanger, ‘The Contemporary Law of Blockade and the Gaza Freedom Flotilla’ (2010) 13 Yearbook of International Humanitarian Law 397, 426 ff; Russell Buchan, ‘The International Law of Naval Blockade and Israel’s Interception of the Mavi Marmara’ (2011) 58 Netherlands International Law Review 209, 216 ff.

36  See Yoram Dinstein, The International Law of Belligerent Occupation (Cambridge: Cambridge University Press, 2009), 276 ff; HCJ 769/02 Public Committee Against Torture v. Government (2006); 2 IsrLR 459 (2006); The Public Commission to Examine the Maritime Incident of 31 May 2010, The Turkel Commission (Jan 2010), para 44; Palmer Report, para. 73. It should be noted that the authors referred to in n 35 are hesitant to bluntly deny the existence of an international armed conflict.

37  See only Tucker, The Law of War and Neutrality at Sea, 335 fn 1; Colombos, International Law of the Sea, 769 ff.

38  San Remo Manual, paras 98, 146, 153; Declaration concerning the Laws of Naval War, Art 63, London, 26 Feb 1909. See also Tucker, The Law of War and Neutrality at Sea, 336; Colombos, International Law of the Sea, 770.

39  San Remo Manual, para 102; HPCR Manual, Rule 153.

40  San Remo Manual, para 103; HPCR Manual, Rule 158.

41  With regard to the different evaluations of the situation in Gaza, see Guilfoyle, ‘The Mavi Marmara Incident and Blockade in Armed Conflict’, 198 ff; Buchan, ‘The International Law of Naval Blockade and Israel’s Interception of the Mavi Marmara’, 232 ff; Sanger, ‘The Contemporary Law of Blockade and the Gaza Freedom Flotilla’, 435 ff; Palmer Report, 68 ff. It needs to be emphasized that the blockading power may prescribe the technical arrangements, including search, under which relief consignments are permitted. Moreover, it may be recalled that, in 2010, the Israeli government was prepared to allow the shipment of the flotilla’s cargo to Gaza under the condition that it was unloaded in an Israeli port and that its distribution was entrusted to the UN. That proposal was well in accordance with the applicable law.

42  San Remo Manual, para 98.

43  San Remo Manual, para 98. See also HPCR Manual, Rule 174.

44  See the references in nn 37 and 38.

45  See the references in nn 37 and 38.

46  Sanger, ‘The Contemporary Law of Blockade and the Gaza Freedom Flotilla’, 438 ff; Buchan, ‘The International Law of Naval Blockade and Israel’s Interception of the Mavi Marmara’, 237 ff; Palmer Report, 61; Turkel Report, 263 ff.

47  See the contributions in Elleman and Paine, Naval Blockades and Seapower; further Wolff Heintschel von Heinegg, ‘Naval Blockade’ in Michael N. Schmitt (ed), ‘International Law Across the Spectrum of Conflict: Essays in Honour of Professor L. C. Green on the Occasion of His Eightieth Birthday’ (2000) 75 International Law Studies 203–30.

48  The same obligation arises from Art 25 of the UN Charter in the case of a binding decision taken by the UN Security Council under Chapter VII explicitly or implicitly authorizing the establishment of a blockade.

49  See also Michael A. Becker, ‘The Shifting Public Order of the Oceans: Freedom of Navigation and the Interdiction of Ships at Sea’ (2005) 46 Harvard International Law Journal 131; Douglas Guilfoyle, Shipping Interdiction and the Law of the Sea (Cambridge: Cambridge University Press, 2009); Wolff Heintschel von Heinegg, ‘UNCLOS and Maritime Security Operations’ (2005) 48 German Yearbook of International Law 151.

50  See Lois E. Fielding, Maritime Interception and U.N. Sanctions (San Francisco, CA: Austin & Winfield, 1997).

51  See only Fink, ‘The Right of Visit for Warships’, 12 ff.

52  See Tullio Treves, ‘Piracy, Law of the Sea, and Use of Force: Developments off the Coast of Somalia’ (2009) 20 European Journal of International Law 399; Wolff Heintschel von Heinegg, ‘Repressing Piracy and Armed Robbery at Sea—Towards a New International Legal Regime?’ (2010) 40 Israel Yearbook on Human Rights 219.

53  Michael Byers, ‘Policing the High Seas: The Proliferation Security Initiative’ (2004) 98 American Journal of International Law 526; Wolff Heintschel von Heinegg, ‘The Proliferation Security Initiative—Security vs. Freedom of Navigation?’ (2005) 35 Israel Yearbook on Human Rights 181.

54  See Daniel H. Joyner, ‘The Implications of the Proliferation of Weapons of Mass Destruction for the Prohibition of the Use of Force’, Chapter 48 and Douglas Guilfoyle, ‘The Use of Force against Pirates’, Chapter 49 both in this volume.

55  San Remo Manual, paras 112–58; HPCR Manual, Section U.

56  See Craig H. Allen, ‘A Primer on the Non-Proliferation Regime for Maritime Security Operation Forces’ (2007) 54 Naval Law Review 51, who rightly states that maritime interception operations (MIOs), have become a ‘familiar element in the daily routine of units assigned to the maritime component of combined and joint forces commands’ (at 51).

57  Terry D. Gill and Dieter Fleck (eds), The Handbook of the International Law of Military Operations (Oxford: Oxford University Press, 2010), para 20.01.

58  With regard to the different purposes of maritime zones and their legal bases, see Richard Jacques, Maritime Operational Zones (Newport, RI: US Naval War College, 2006).

59  See Michael N. Schmitt, ‘Air Law and Military Operations’ in Gill and Fleck, The Handbook of the International Law of Military Operations, paras 18.05, 18.06, 18.07, 18.12, and accompanying commentary.

60  Convention for the Suppression of Unlawful Acts Against the Safety of Maritime Navigation (SUA Convention), Rome, 10 Mar 1988, 1678 UNTS 221; reprinted in (1988) 27 ILM 668. Protocol for the Suppression of Unlawful Acts against the Safety of Fixed Platforms Located on the Continental Shelf, Rome, 10 Mar 1988, 1678 UNTS 304; Protocol of 2005 to the Convention for the Suppression of Unlawful Acts Against the Safety of Maritime Navigation, London, 14 Oct 2005, IMO Doc LEG/CONF. 15/21; Protocol of 2005 to the Protocol for the Suppression of Unlawful Acts against the Safety of Fixed Platforms Located on the Continental Shelf, London, 14 Oct 2005, IMO Doc LEG/CONF. 15/22.

61  UNCLOS, Art 27(5). Note, however, that this restriction does not apply to cases provided for in UNCLOS Part XII on the protection of the marine environment or with respect to violations of laws and regulations adopted in accordance with Part V.

62  UNCLOS, Art 33.

63  Churchill and Lowe, The Law of the Sea, 137.

64  UNCLOS, Art 111.

65  According to UNCLOS, Art 110(4), ‘these provisions apply mutatis mutandis to military aircraft.’

66  UNCLOS, Art 110(2).

67  See also Stuart Kaye, ‘Threats from the Global Commons: Problems of Jurisdiction and Enforcement’ in Michael D. Carsten (ed), ‘Global Legal Challenges: Command of the Commons, Strategic Communications and Natural Disasters’ (2007) 86 International Law Studies 69, 74 ff.

68  The agreements are available at <http://www.state.gov/t/isn/trty/index.htm>.

69  See, inter alia, the Agreement concerning Cooperation in Suppressing Illicit Maritime and Air Trafficking in Narcotic Drugs and Psychotropic Substances in the Caribbean Area, San Jose, 10 Apr 2003.

70  For the legality of the use of force in maritime interdiction operations, see Wolff Heintschel von Heinegg, ‘Maritime Interception/Interdiction Operations’ in Gill and Fleck, The Handbook of the International Law of Military Operations, para 20.12 and accompanying commentary.

71  San Remo Manual, paras 112–58; HPCR Manual, Section U; ILA Helsinki Principles, para 5.2.

72  See n 32 and accompanying text.

73  Norman J. Padelford, ‘Foreign Shipping During the Spanish Civil War’ (1938) 32 American Journal of International Law 264.

74  Laurent Lucchini, ‘Actes de contrainte exercés par la France en Haute Mer au cours des opérations en Algérie’ (1966) Annuaire Français de Droit International 803. See also Daniel P. O’Connell, ‘International Law and Contemporary Naval Operations’ (1970) 44 British Yearbook of International Law 19, 36 ff.

75  Guilfoyle, ‘The Mavi Marmara Incident and Blockade in Armed Conflict’, 193.

76  See the references in nn 73 and 74.

77  In 2008 and until the establishment of the blockade of Gaza on 3 Jan 2009, Israel exercised the right of visit and search in order to prevent the flow of arms into the Gaza Strip. It seems that the few measures taken against foreign vessels that were suspected, on reasonable grounds, of being engaged in the transportation of arms destined to the Hamas, did not give rise to strong protests. Either the flag states implicitly recognized Israel’s security interests or they simply did not want to admit that the ships flying their flags had been engaged in the smuggling of arms and ammunition.

78  Guilfoyle, ‘The Mavi Marmara Incident and Blockade in Armed Conflict’, 193 ff.

79  Prize measures are part of the law of neutrality that does not apply to situations of non-international armed conflict. See James Kraska, ‘Prize Law’ in Wolfrum, Max Planck Encyclopedia of Public International Law, vol VIII, 477.

80  Jean-Marie Henckaerts and Louise Doswald-Beck (eds), Customary International Humanitarian Law (Cambridge: Cambridge University Press, 2005), vol I (Rules), 30 ff; Michael N. Schmitt, Charles H. B. Garraway, and Yoram Dinstein, The Manual on the Law of Non-International Armed Conflict. With Commentary (San Remo, Mar 2006), para 1.1.4.

81  eg the measures taken by France in the course of the Algerian conflict and those taken by the Sri Lankan government during the long-lasting conflict with the Tamil Tigers were not protested by all states whose vessels were affected.

82  Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory, Advisory Opinion, ICJ Rep 2004, para 139: ‘The Court also notes that Israel exercises control in the Occupied Palestinian Territory and that…the threat which it regards as justifying the construction of the wall originates within, and not outside, that territory. The situation is thus different from that contemplated by Security Council resolutions 1368 (2001) and 1373 (2001)…Consequently, the Court concludes that Article 51 of the Charter has no relevance in this case.’

83  See only UNCLOS, Art 92(1).

84  See also Fink, ‘The Right of Visit for Warships’, 36 ff.

85  NWP 1-14M, para 3.11.2.5.2.

86  NWP 1-14M, para 3.11.2.5.2. See also David G. Wilson, ‘Interdiction on the High Seas: The Role and Authority of a Master in the Boarding and Searching of His Ship by Foreign Warships’ (2008) 55 Naval Law Review 157.

87  Wilson, ‘Interdiction on the High Seas’, 157.

88  Wilson, ‘Interdiction on the High Seas’, 157.

89  Heintschel von Heinegg, ‘Maritime Interception/Interdiction Operations’ in Gill and Fleck, The Handbook of the International Law of Military Operations, 375.

90  SC Res 661 of 6 Aug 1990.

91  Richard D. Zeigler, ‘Ubi Sumus? Quo Vadimus? Charting the Course of Maritime Interception Operations’, Naval War College Paper, Newport, RI, 1995, 69, also published in (1996) 43 Naval Law Review 1.

92  SC Res 661, para 3.

93  According to Zeigler, ‘Ubi Sumus?, 119, ‘there were, between August 17, 1990 and 28 February 1991, only eleven warning shots fired, no use of disabling fire, only eleven takedown actions, and a mere 51 diversions of vessels. Most of the warning shots were fired by U.S. vessels early in the operation, even before August 25, 1990, the effective date of U.N. Security Council Resolution 665.’

94  SC Res 678 of 29 Nov 1990.

95  See only Fink, ‘The Right of Visit for Warships’, 30 ff.

96  See only Fink, ‘The Right of Visit for Warships’, 30 ff.

97  NWP 1-14M, para 4.4.7.

98  For the establishment of exclusion zones under the law of international armed conflict, see San Remo Manual, paras 105–8; HPCR Manual, Section P.

99  For a theoretical example, see Wolff Heintschel von Heinegg, ‘Current Legal Issues in Maritime Operations: Maritime Interception Operations in the Global War on Terrorism, Exclusion Zones, Hospital Ships and Maritime Neutrality’ in Richard B. Jaques (ed), ‘Issues in International Law and Military Operations’ (2006) 80 International Law Studies 207, 214 ff.

100  SC Res 1373 of 28 Sept 2001.

101  SC Res 1540 of 28 Apr 2004.

102  International Law Commission, Responsibility of States for Internationally Wrongful Acts, Arts 22 and 49–53, GA Res 56/83 Annex, A/RES/56/83 (12 Dec 2001).

103  See Heintschel von Heinegg, ‘Current Legal Issues in Maritime Operations’ in Jaques, Issues in International Law and Military Operations, 213.