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The Use of Force in International Law - A Case-Based Approach edited by Ruys, Tom; Corten, Olivier; Hofer, Alexandra (17th May 2018)

Part 1 The Cold War Era (1945–89), 18 The Mayaguez Incident—1975

Natalino Ronzitti

From: The Use of Force in International Law: A Case-Based Approach

Edited By: Tom Ruys, Olivier Corten, Alexandra Hofer

From: Oxford Public International Law (http://opil.ouplaw.com). (c) Oxford University Press, 2015. All Rights Reserved. Subscriber: null; date: 14 December 2019

Precedent — Territorial sea — Armed forces

(p. 213) 18  The Mayaguez Incident—1975

I.  Facts and Context

The Mayaguez incident is one of the leading cases for asserting the legality of rescuing nationals abroad and also for considering the legality of actions against ships under the law of the sea.1 The incident involved Cambodia, then under the rule of the Khmer Rouge, and the United States. The Mayaguez was a cargo ship en route from Hong Kong to Thailand. On 12 May 1975, it was boarded and captured by Cambodian naval gunboats while it was off the coast of Poulo Way Island and obliged to anchor off the Koh Tang Island. The United States demanded the release of the ship within twenty-four hours. After the seizure, the Cambodian authorities tried to move the Mayaguez crew to the mainland. The United States, considering that the removal to the mainland would render the rescue operation more difficult, attacked the Cambodian gunboats escorting the Mayaguez and Cambodia was obliged to disembark the crew in an island close to the mainland. An assault was launched on 15 May 1975 against a Khmer Rouge force stationed on the island of Koh Tang and at the same time against military objectives on the mainland. The US operation caused heavy losses. Three helicopters were shot down, eighteen soldiers were killed or went missing, and twenty-three lost their life in a helicopter crash.2 During the operation, a US boarding party took control of the Mayaguez. The ship, which was empty, was towed to international waters. The Mayaguez crew, which the Cambodian authorities had previously boarded upon a Thai fishing vessel, was subsequently taken on board by (p. 214) the US destroyer Wilson. This meant that the Cambodians had freed all sailors, in conformity with a communiqué stating the following:

Regarding the Mayaguez ship we have no intention of detaining it permanently and we have no desire to stage provocations. We only wanted to know the reason for its coming and to warn it against violating our waters again. This is why our coastguard seized this ship. Their goal was to examine it, question it and make a report to higher authorities who would then report to the Royal Government so that the Royal Government could itself decide to order it to withdraw from Cambodia’s territorial waters and warn it against conducting further espionage and provocative activities. This applies to this Mayaguez and to any other vessels like the ship flying Panama flag that we released on May 7, 1975.

Wishing to provoke no one or to make trouble, adhering to the stand of peace and neutrality, we will release this ship, but we will not allow the US imperialists to violate our territorial waters, conducting espionage in our territorial waters, provoke incidents in our territorial waters or force us to release their ships whenever they want by applying threats.3

In 1977, a number of lawsuits in admiralty were filed against the ship-owners and the US Government by the crew of the Mayaguez before the San Francisco Superior Court of the State of California. The actions against the ship-owners were concluded with a settlement awarding compensation. It was asserted that the Mayaguez ventured in foreign territorial waters, 1.75 miles off a Cambodian Island. Moreover, it was claimed that the ship entered the Cambodian waters without flying any flag for carrying out an espionage mission and having on board a cargo of weapons. Since the controversy was concluded with a settlement, it is not possible to establish the veracity of those claims on the basis of a court verdict.

II.  The Position of the Main Protagonists and the Reaction of Third States and International Organizations

The main protagonists, that is, the United States and Cambodia, obviously had opposite interpretations concerning the legality of the actions undertaken throughout the course of events.

The immediate reaction by the United States was that the seizure of the Mayaguez was an ‘act of piracy’ committed in international waters. The White House Press release of 12 May 1975 stated as follows:

We have been informed that a Cambodian naval vessel has seized an American merchant ship on the high seas and forced it to the port of Kompong Som. The President has met with the National Security Council. He considers this seizure an act of piracy.4

Immediately after the seizure, the United States prepared a contingency plan, involving the use of force, to ‘avoid another Pueblo’.5 At the same time, it tried to solve the crisis by (p. 215) peaceful means, requesting the release of the crew and the vessel. Since the United States did not have any diplomatic channel with Cambodia, it asked the Chinese liaison office in Washington to deliver the note to Cambodia. The Chinese authorities refused to do so and the United States tried again with the Minister of Foreign Affairs in Peking, who refused and returned the diplomatic note to the United States. Moreover, the United States asked for the support and good offices of the UN Secretary-General, Kurt Waldheim, pointing out that the illegal and unprovoked seizure of the Mayaguez constituted a threat to international peace. The note concluded that the United States reserved the right to take ‘such measures as may be necessary to protect the lives of American citizens and property, including appropriate measures of self-defence under Article 51 of the UN Charter’.6

Yet, the UN Secretary-General’s efforts did not obtain any results and the Cambodian authorities did not show the willingness to be collaborative. Some days later, on 21 May, the Cambodian Prince Norodom Sihanouk affirmed that his government did not know of any attempt made by the United States to solve the crisis peacefully.

It was then that the United States decided to have recourse to the use of force and informed the Security Council of the measures taken. The letter, dated 14 May 1975, recalls the factual grounds of the Mayaguez seizure and concludes as follows:

The United States Government immediately took steps through diplomatic channels to recover the vessel and arrange the return of the crew. It earnestly sought the urgent co-operation of all concerned to this end, but no response has been forthcoming. In these circumstances the United States Government has taken certain appropriate measures under Article 51 of the United Nations Charter whose purpose is to achieve the release of the vessel and its crew.7

Cambodia rejected all US arguments. First, it said that the ship was in Cambodia’s territorial waters conducting espionage operations; second, it asserted that it was considering freeing the ship and its crew when the US intervention took place.8 Therefore Cambodia regarded the US intervention as totally unjustified, an act of aggression, and a blatant violation of international law.

The reaction of third states hinted at a violation of international law by the United States. China affirmed that the Mayaguez was in Cambodia’s territorial waters. The Vice Premier Li Hsien-nien stated that the United States had committed an ‘outright act of piracy’ adding that the Mayaguez had invaded Cambodia’s territorial waters obliging Cambodia to take ‘legitimate measures’ against the ship to safeguard her state sovereignty.9 Algeria qualified the US raid as a case of armed aggression.10 Criticism was also expressed by Thailand as the raid had departed from the US airbase of U-Tapao in Thailand, without the consent of the Thai Government, and the United States had promised not to use their bases in Thailand for military operations in the area.11 It seems, however, that the United States had obtained permission to use the airbase for the rescue mission from the Thai military. Nevertheless, the Thai Government did not take position on the lawfulness of the US rescue operation.

There was no significant reaction on behalf of international organizations. As mentioned above, the United States notified the Security Council about the measures undertaken (p. 216) claiming the right of self-defence. However, the issue was not debated within the Security Council or any other organ of the United Nations. The UN Secretary-General tried to exert his good offices in order to solve the crisis but did not release any statements after the American operation.

III.  Questions of Legality

The legality of the measures taken respectively by the United States and Cambodia depends on the factual background and the course of events. As the actual facts are not without controversy, one is obliged to reach different conclusions based on the scenario taken into consideration.

The first question is related to the location of the Mayaguez at the time of its seizure. If we accept that the ship was in international waters, the seizure was totally unjustified even if one assumes that the ship was conducting an intelligence mission. Spying from an international zone, be it the high seas or outer space, does not constitute an internationally wrongful act.12 By contrast, if the ship was within Cambodia’s territorial waters, it was entitled to exercise its right of innocent passage, which nonetheless forbids any activity inconsistent with the peace, good order, and security of the coastal state. Espionage is clearly inconsistent with innocent passage and the coastal state has the right to take ‘necessary steps’, which may involve the capture of the ship and subjecting the crew to the criminal jurisdiction of the coastal state. As far as the present case is concerned, the issue is complicated by the fact that the law of the sea in force at the time did not establish a clear rule for the breadth of the territorial sea, which was codified only by the 1982 United Nations Convention on the Law of the Sea (UNCLOS). A fixed rule on the limit of the territorial sea was absent in the 1958 Geneva Convention on Territorial Sea and the Contiguous Zone. At the time, the United States recognized only a 3-mile limit to the territorial sea, while Cambodia, similar to other developing countries, recognized a 12-mile limit.13 According to the United States, the Mayaguez was navigating in a well-recognized shipping lane at 6.5 miles from the coast. However, even assuming that the ship was only 1.5 miles from the coast, it was entitled to cross the territorial sea in innocent passage. The only rationale for seizing the ship would be its employment in an intelligence mission, a fact denied by the United States, which also stated that the ship did not carry any weapons.

The US qualification of the seizure of the Mayaguez as an act of piracy is deprived of any legal meaning. According to customary international law, as embodied in Article 15(1) of the 1958 Geneva Convention on the high seas, the seizure of a foreign ship can be labelled as an act of piracy provided that it is operated by a private ship (or a warship whose crew has mutinied) for private ends (the so-called animus furandi) and takes place on the high seas.14 In the case concerned, the seizure was operated by a warship in order to ascertain whether the ship was carrying out an espionage mission. Therefore, the claim that the Cambodian authorities committed an act of piracy is without legal basis, even if it is assumed that the seizure occurred on the high seas and not when the ship was within the Cambodian territorial waters.

(p. 217) What about the use of force by the United States in order to free the crew? The United States wanted to prevent the Mayaguez from reaching the mainland and therefore, before launching an assault against the island of Koh Tang, tried to obtain the release of the crew through diplomatic means, requesting the cooperation of China and the good offices of the UN Secretary-General. Thus, they tried to achieve the result peacefully, while not ruling out the use of force. This was, however, a contingency plan and not an ultimatum implying the use of force. When the United States launched their operation, they invoked the right of self-defence under Article 51 of the UN Charter and communicated the measures taken to the Security Council. Could the US action be justified under the right of self-defence or would other justifications be more appropriate?15 Supposing that the Mayaguez was navigating on the high seas or navigating Cambodia’s territorial waters in innocent passage, could the seizure of a private ship be considered an ‘armed attack’? It is clear that an attack against a military vessel triggers the right of self-defence, as illustrated by Article 6 of the North Atlantic Treaty that affirms that an attack against a vessel of a member state in the zone covered by the Treaty sets in motion the duty of military assistance referred to in Article 5. Article 3(d) of the UNGA’s Definition of Aggression (Resolution 3314 (XXIX)) qualifies the attack against the ‘marine and air fleets’ of another state as an act of aggression—this provision presupposes an attack on a large scale and not an attack against a single unit, as may be drawn from the drafting history of the Resolution. However, from the Oil Platforms case one might infer that an attack against a merchant ship may also be equated to an attack against the flag state.16 There is also a body of opinion that considers an attack against a state’s citizens abroad as an attack against the national state, on the premise that the citizens abroad are an extension of the state territory.17 However, this opinion, leaving aside its basis in international law, cannot be applied to the Mayaguez, since it is formulated in connection with the protection of a large number of people and not in connection with a few individuals. The doctrine of intervention to rescue nationals abroad is sound ground for using force for limited purposes. According to the United States, a right of intervention to rescue citizens abroad is permissible under international law.18 It is a right, already in existence (p. 218) before the adoption of the UN Charter, which has survived notwithstanding the general prohibition of the use of force enshrined in Article 2(4) of the UN Charter.19 As practice shows, this doctrine has gained currency not only among western states, but also among developing countries20 and has been also endorsed by the Russian Federation.21 The problem with the Mayaguez incident is whether the doctrine under consideration may be applied to the case in question. The use of force for protecting nationals abroad is conditional, like any other use of force, upon a number of requirements, first of all necessity and proportionality. Leaving aside the requirement of proportionality, it is to be inquired whether there was a real necessity for intervention. This depends on the assertion by Cambodia that it would free the crew and its timely reception by the United States. In reality, the Cambodian Communiqué, which was delivered on 15 May at 06:20 am (Cambodian time) did not clearly mention the crew, but only the ship, and this caused President Gerald Ford not to discontinue the operation. The White House said that the United States was prepared to stop the military action as soon as Cambodia was willing to release the crew ‘unconditionally and immediately’. As a matter of fact, there was a gap in communication, since all exchanges between the two governments took place through radio broadcast or press agencies in the absence of diplomatic relations between Cambodia and the United States. This is the reason why the United States cannot be accused of having disregarded the requirement of necessity by having set in motion a military expedition notwithstanding the promise by Cambodia to free the crew. There is, however, another criterion for evaluating the legality of the rescue operation. For those who admit such a right, this is allowed under international law, provided that the national state or its citizens have not created the danger. If the Mayaguez was indeed conducting an espionage mission in Cambodian territorial waters, the rescue operation would be without any legal basis.

IV.  Conclusion: Precedential Value

The US action to rescue the Mayaguez is an example of an interventionist policy that was criticized not only by the targeted state and other South-East Asian countries, but also by (p. 219) a number of American writers for faulty coordination and because the United States was obliged to pay reparations to the victims. These criticisms are of a political and military nature. From a legal point of view, the Mayaguez precedent has little value; its main value is related both to the doctrine of intervention for protecting nationals abroad and to the notion of armed attack, more precisely with regard to the nature of the assets which, when attacked, entitle the targeted state to trigger the right of self-defence. In fact, the United States followed a two-track approach asserting both the right of protecting nationals abroad and the right of self-defence, when it notified the UN Secretary-General that the United States reserved the right to take ‘such measures as may be necessary to protect the lives of American citizens and property, including appropriate measures of self-defence under Article 51 of the U.N. Charter’.22 It follows that the incident should be situated between the practice corroborating the existence of a right to intervene for rescuing nationals abroad, which is different from self-defence, and constitutes a further exception to the prohibition of the use of force set forth by Article 2(4) of the UN Charter, and the practice concerning the right of self-defence. From the latter point of view, the incident is connected with the notion of armed attack, triggering the right of self-defence. The United States regarded the seizure of the Mayaguez as an ‘armed attack’, thus contributing to the doctrine that not only a forceful action against a military ship constitutes an armed attack but also the seizure of a merchant ship.

Aside from these considerations, the incident has little precedential value. The labelling of the seizure as an act of piracy was clearly a mistake and a political statement: it does not contribute to changing the law of the sea in this respect. The same is true, mutatis mutandis, for the navigational rights of a foreign vessel. These rights depend on the location of the ship, whether it is navigating on the high seas or traversing foreign territorial waters. Furthermore, the question of the territorial sea limit is now resolved by the UNCLOS, and the United States recognizes 12-mile limits for the territorial sea, even though it is not a party to the Law of the Sea Convention. Finally, the claim that the Mayaguez was not flying any flag is not a valid justification for capturing it. If a commercial ship navigates without showing a flag, this does not mean that the ship is without nationality. The coastal state has a right to approach and to ask the nationality of the ship. This is true not only on the high seas, but also with regard to innocent passage in territorial waters, as it may be drawn from the rule that only submarines are explicitly requested to navigate on the surface and show their flag.

In conclusion, the Mayaguez incident is insightful with regard to the doctrine of rescuing nationals abroad. Perhaps one may also add that the attempt to terminate the crisis by diplomatic means before setting in motion a military action serves as a precedent affirming that states should try to use peaceful means before having recourse to the use of force.


1  The Mayaguez incident has been the object of a number of comments by international lawyers immediately after the events as well as in later years. See Charles F Bennet, ‘The Mayaguez Re-examined: Misperception in an Information Shortage’ (1976) 1 The Fletcher Forum 15; Jordan J Paust, ‘The Seizure and the Recovery of the Mayaguez’ (1976) 85 Yale Law Journal 774; Charles Rousseau, ‘Cambodge et Etats-Unis, Affaire du Mayaguez, Arraissonnement et arrestation d’un cargo américain dans le Golfe de Siam par les forces armées cambodgiennes (12 mai 1975). Libération du navire per les forces américaines (15 mai 1975)’ (1976) LXXX Revue générale de droit international public 222; Robert Zutz, ‘The Recapture of the S.S. Mayaguez: Failure of the Consultation Clause of the War Powers Resolution’ (1975) 8 New York University Journal of International Law and Politics 457; Stephen B Finch, ‘Pueblo and Mayaguez; A Legal Analysis’ (1977) 9 Case Western Reserve Journal of International Law 79; Robert A Friedlander, ‘The Mayaguez in Retrospect: Humanitarian Intervention or Showing the Flag?’ (1978) 22 St Louis University Law Journal 601; Thomas E Behuniak, ‘The Seizure and Recovery of the S.S. Mayaguez: A Legal Analysis of the United States Claims’ (1978) 82 Military Law Review 41; Robert R Simmons, ‘The Pueblo, EC-121, and Mayaguez Incidents: Some Continuities and Changes’ (1978) 20 Occasional Papers/Reprints, Series in Contemporary Asian Studies; Jordan J Paust, ‘More Revelations About Mayaguez (and its Secret Cargo)’ (1981) 4 Boston College and International and Comparative Law Review 61; Natalino Ronzitti, Rescuing Nationals Abroad Through Military Coercion an Intervention on Grounds of Humanity (Martinus Nijhoff Publications 1985) 35–36. For a narration of facts see ‘Seizure of the Mayaguez, Hearings before the Subcommittee on International Relations, House of Representative’, Ninety-Fourth Congress, First Session, Part II, 19 June and 25 July 1975. US Government Printing Office (1975) 229–54; Keesing’s Record of World Events (formerly Keesing’s Contemporary Archives) (21–27 July 1975) XXI, United States, Cambodia, Thailand, 27239–40. See also Chris Lamb, ‘Belief Systems and Decision Making in the Mayaguez Crisis’ (1984) 99 Political Sciences Quarterly 681; ‘Mayaguez Incident’, The Oxford Encyclopedia of American Military and Diplomatic History (OUP 2013).

2  However, the number of casualties varies from one source to another: see for instance Keesing’s Contemporary Archives (n 1) 27239.

3  May 15 Cambodian Communiqué offering to release the Mayaguez, reprinted in Behuniak (n 1) Appendix C, 165–66; Keesing’s Contemporary Archives (n 1) 27239. As a matter of fact, the shipmaster had convinced the Cambodian authorities that the Mayaguez did not carry any weapons and was not engaged in an espionage mission.

4  The Department of State Bulletin, LXXII, No 1875 (2 June 1975) 719.

5  The Pueblo was a US navy vessel, disguised as a fishing boat but, in reality, carrying out an espionage mission off the North Korean coast. It was captured by North Korea on 23 January 1968 and the crew was imprisoned. The US sailors were released on 23 December 1968 after the United States admitted they intruded the North Korean territorial waters and apologized for violating its sovereignty. See Chapter 14, ‘The USS Pueblo Incident—1968’ by Wolff Heintschel von Heinegg in this volume.

6  The Department of State Bulletin, LXXII, No 1875 (2 June 1975) 720.

7  Letter dated 14 May 1975 from the Permanent Representative of the United States of America to the United Nations addressed to the President of the Security Council (15 May 1975) UN Doc S/11689.

8  Keesing’s Contemporary Archives (n 1) 27239.

9  Foreign Relations of the United States X (1969–76) 1041.

10  ‘ “Mayaguez” Incident, Another US Imperialist Struggle in Desperation’, Peking Review (23 May 1975) 11.

11  Keesing’s Contemporary Archives (n 1) 27239.

12  See, generally, Simon Chesterman, ‘Secret Intelligence’ (2009) Max Planck Encyclopedia of Public International Law. As far as the law of the sea is concerned, Article 19(2)(c) of UNCLOS lists intelligence gathering as an activity that constitutes a violation of innocent passage. However, UNCLOS does not contain a prohibition from carrying out such an activity from the high seas.

13  Behuniak (n 1) 104.

14  James Crawford, Brownlie’s Principles of Public International Law (8th edn, OUP 2012) 303.

15  According to Alexandrov, the lawfulness of the US action is questionable on several grounds, since it is doubtful if self-defence may be invoked for an attack against a merchant ship or for rescuing citizens abroad. Moreover, the action by the United States was not justified in terms of necessity and proportionality: Stanimir A Alexandrov, Self-Defense Against the Use of Force in International Law (Kluwer Law International 1996) 194–95. See also, Tom Ruys, ‘Armed Attack’ and Article 51 of the UN Charter: Evolutions in Customary Law and Practice (CUP 2010) 211 and 224–25.

16  Oil Platforms (Islamic Republic of Iran v United States of America) (Judgment) (2003) ICJ Rep 161 [64]. The Court considered the case of three merchant ships. The Bridgeton, a US-flagged vessel, was struck by a mine, but it was not proven that the mine was placed with the specific intention of mining the ship; the Sea Isle City was a US ship anchored in Kuwaiti waters, but it was not a specific target of a Silkworm missile fired from more than 100 km away; the Texaco Caribbean was not flying a US flag. Thus, the Court did not say that the action by Iran did not qualify as an armed attack since the action was directed against a merchant ship. It applied a different reasoning. See Ruys (n 10) 207–09 on the lawfulness of on-the-spot measures of self-defence, provided that the merchant vessel is not navigating in the territorial waters of the coastal state. According to Karl Zemanek (‘Armed Attack’ (2013) Max Planck Encyclopedia of Public International Law) ‘an armed attack even when it consists of a single incident, which leads to a considerable loss of life and extensive destruction of property, is of sufficient gravity to be considered an armed attack in the sense of Art. 51 UN Charter’.

17  Christian Tomuschat, ‘International Law: Ensuring the Survival of Mankind on the Eve of a New Century’, General Course on Public International Law (vol 281) Collected Courses of the Hague Academy of International Law (The Hague Academy of international Law 1999) 215–16. Tomuschat makes a distinction between an attack against isolated individuals and massive and systematic attacks against groups of individuals who become the object of violence because of their nationality. Only in the latter case will the attack be equivalent to an attack against the state of nationality of the individuals, which will be entitled to react in self-defence.

18  See Ronzitti (n 1), 53-54.

19  See Natalino Ronzitti, Introduzione al diritto internazionale (5th edn, Giappichelli 2016) 444–46. Other authors are more sceptical. See, for instance, Mathias Forteau, ‘Rescuing Nationals Abroad’ in Marc Weller (ed), The Oxford Handbook of the Use of Force in International Law (OUP 2015) 961: ‘The issue of the legality of the use of force to rescue nationals abroad actually remains largely undecided.’

20  For instance, Egypt intervened in Larnaca (1978) (Ronzitti (n 1) 40–41) and in Malta (1985) to free its citizens that were taken hostage by terrorists (even though it seems that in the latter case Egypt was given the permission by the Maltese authorities to storm the hijacked plane: The Washington Post (25 November 1985) 445. Contra Olivier Corten, The Law Against War: The Prohibition on the Use of Force in Contemporary International Law (Hart Publishing 2010), who cites the work of the International Law Commission on Diplomatic Protection (2005) and in particular the refusal to accept the proposal submitted by Rapporteur Dugard to admit the existence of a right to use force to rescue nationals abroad (523–27). According to Corten there is no conclusive set of precedents substantiating a right to intervene in foreign territory for protecting a state’s own nationals (546–48).

21  On 8 August 2008, the Russian President Medvedev released the following declaration: ‘In accordance with the Constitution and the federal laws, as president of the Russian Federation it is my duty to protect the lives and dignity of Russian citizens wherever they may be.’ (Martin Dixon, Robert McCorquodale, and Sarah Williams, Cases and Materials on International Law (OUP 2011) 620). Subsequently, the Duma adopted an amendment (23 October 2009) to the law on defence of the Russian Federation stating that the defence of Russian citizens abroad is a valid justification for sending troops outside the national borders (see European Commission for Democracy Through Law—Venice Commission—Opinion on the Amendments to the Federal Law on Defence of the Russia Federation, Venice 17–18 December 2010, Opinion no 57272010, 4). The right of intervention is also enshrined in the Russian military doctrine of 25 December 2014 (the Military Doctrine of the Russian Federation, approved by the President of the Russian Federation on December 25, 2014, No Pr-2978: rusemb.org.uk/press 2029).

22  See Behuniak (n 1) Part 2, 119.