1 For a discussion of the jus ad bellum and for the contrary view, see Ruys, Tom, “Armed Attack” and Article 51 of the UN Charter: Evolutions in Customary Law and Practice, Cambridge University Press, Cambridge, 2010Google Scholar, pp. 204 ff.

2 The term “merchant vessel” as used here applies to all vessels that are not State ships – i.e., cargo ships, cruise ships, yachts etc. which are not used for exclusively governmental, non-commercial purposes.

3 ICRC, Commentary on Convention (II) for the Amelioration of the Condition of the Wounded, Sick and Shipwrecked Members of Armed Forces at Sea, Geneva, 12 August 1949, 2nd ed., 2017 (online version) (ICRC Commentary on GC II), Art. 2, “Application of the Convention”, para. 233.

4 Ibid., para. 235, 240, inter alia referring to the Tadić judgment.

5 Ibid., para. 247.

6 Ibid., para. 248. See also para. 251: “Even if armed conflicts under Article 2(1) generally imply the deployment and involvement of military means, there might be situations in which the use of force by other State officials or persons qualified as ‘agents’ of a State would suffice. However, only the use of force by the de jure or de facto organs of a State, but not by private persons, will constitute an armed conflict.”

7 Ibid., paras 258 ff. In this context, the ICRC recognizes the position of some States, which have considered that an international armed conflict triggering the application of the Geneva Conventions had come into existence after the capture of just one member of their armed forces (para. 260). See also paras 264 ff., where the ICRC rejects the position according to which an international armed conflict requires a certain intensity and duration.

8 Ibid., para. 263.

9 According to the UN Convention on the Law of the Sea (UNCLOS), 1833 UNTS 3, 297, 10 December 1982, Art. 29, “warship” is defined as “a ship belonging to the armed forces of a State bearing the external marks distinguishing such ships of its nationality, under the command of an officer duly commissioned by the government of the State and whose name appears in the appropriate service list or its equivalent, and manned by a crew which is under regular armed forces discipline”. For a discussion of those elements, see Wolff Heintschel von Heinegg, “Warships”, Max Planck Encyclopedia of Public International Law, available at opil.ouplaw.com/view/10.1093/law:epil/9780199231690/law-9780199231690-e443?rskey=nrBmY2&result=4&prd=EPIL (all internet references were accessed in March 2017). According to Rule 1(x) of the HPCR Manual on International Law Applicable to Air and Missile Warfare, Program on Humanitarian Policy and Conflict Research, Harvard University, 2013 (HPCR Manual), “military aircraft” means “any aircraft (i) operated by the armed forces of a State; (ii) bearing the military markings of that State; (iii) commanded by a member of the armed forces; and (iv) controlled, manned pr preprogrammed by a crew subject to regular armed forces discipline”.

10 For the factual findings see International Criminal Court, Office of the Prosecutor, Situation in the Republic of Korea: Article 5 Report, June 2014 (Article 5 Report), pp. 4, 10 ff, available at: www.icc-cpi.int/iccdocs/otp/SAS-KOR-Article-5-Public-Report-ENG-05Jun2014.pdf.

11 Letter from the Permanent Representative of the United States of America to the United Nations addressed to the President of the Security Council, UN Doc. S/2010/398, 23 July 2010, p. 7.

12 Article 5 Report, above note 10, p. 12.

13 For the US Freedom of Navigation Program, see US Department of State, “Maritime Security and Navigation”, available at: www.state.gov/e/oes/ocns/opa/maritimesecurity/.

14 For the facts and an assessment, see Aceves, William J., “Diplomacy at Sea: U.S. Freedom of Navigation Operations in the Black Sea”, International Law Studies, Vol. 68, 1995Google Scholar. See also John H. Cushman Jr., “2 Soviet Warships Reportedly Bump U.S. Navy Vessels”, New York Times, 13 February 1988, available at: www.nytimes.com/1988/02/13/us/2-soviet-warships-reportedly-bump-us-navy-vessels.html.

15 “Harassment” is defined as “repeated, deliberate and intimidating activities intended to discourage, impede and disrupt”. See NATO Glossary, AAP-06(2014), 2014, p. 2-H-1, available at: wcnjk.wp.mil.pl/plik/file/N_20130808_AAP6EN.pdf.

16 See Shirley A. Kan, “The EP-3 Incident and U.S. Interests”, in Shirley A. Kan et al. (eds), China-U.S. Aircraft Collision Incident of April 2001: Assessment and Policy Implications, Congressional Research Service, October 2001, pp. 1 ff.

17 Thomas Frear, Łukasz Kulesa and Ian Kearns, “Dangerous Brinkmanship: Close Military Encounters Between Russia and the West in 2014”, policy brief, European Leadership Network, November 2014, p. 3.

18 “Russia Baltic Military Actions ‘Unprecedented’ – Poland”, BBC News, available at: www.bbc.com/news/world-europe-30429349.

19 Ian Kearns, “Avoiding War in Europa: The Risks from NATO-Russian Close Military Encounters”, Arms Control Association, November 2015, available at: www.armscontrol.org/ACT/2015_11/Features/Avoiding-War-in-Europe-The-Risks-from-NATO-Russian-Close-Military-Encounters#notes.

20 Andrew Tilghman, “Russian Fighter Jet Taunts U.S. Military Aircraft over Baltic Sea”, Military Times, 18 April 2016, available at: www.militarytimes.com/story/military/2016/04/18/russian-fighter-jet-taunts-us-surveillance-aircraft-over-baltic-sea/83188528/.

21 Air interception is “an operation by which aircraft effect visual or electronic contact with other aircraft.” See NATO Glossary, above note 15, p. 2-A-9.

22 Sam LaGrone, “Chinese and Japanese Fighters Clash Over East China Sea”, USNI News, 5 July 2016, available at: https://news.usni.org/2016/07/05/chinese-japanese-fighters-clash-east-china-sea.

23 ICRC Commentary on GC II, para. 259.

24 For the exclusion of ultra vires actions or actions resulting from mistakes, see Ibid., para. 263.

25 Ibid., para. 249.

26 Ibid., para. 263.

27 Ibid., para. 263.

28 Ibid., para. 259.

29 Agreement between the Government of the United States of America and the Government of the Union of Soviet Socialist Republics on the Prevention of Incidents On and Over the High Seas, signed Moscow, 25 May 1972 (entered into force 25 May 1972) (US–USSR Agreement); Protocol to the Agreement between the Government of the United States of America and the Government of the Union of Soviet Socialist Republics on the Prevention of Incidents On and Over the High Seas, signed Washington, 22 May 1973 (entered into force 22 May 1973) (US–USSR Protocol); both available at: www.state.gov/t/isn/4791.htm.

30 USSR–US Agreement on the Prevention of Dangerous Military Activities of 12 June 1989 (entered into force 1 January 1990), International Legal Materials, Vol. 28, No. 4, 1989.

31 Memorandum of Understanding between the Department of Defense of the United States of America and the Ministry of National Defense of the People's Republic of China regarding the Rules of Behavior for Safety of Air and Maritime Encounters, reprinted in Office of the Secretary of Defense, Annual Report to Congress: Military and Security Developments Involving the People's Republic of China 2016, 26 April 2016, Appendix III, pp. 110 ff., available at: www.defense.gov/Portals/1/Documents/pubs/2016%20China%20Military%20Power%20Report.pdf. See also Annex II of the Memorandum of Understanding, “Rules of Behavior for Safety of Surface-to-Surface Encounters”, pp. 117 ff.

32 Ibid., Section VI ii, p. 118.

33 See also USSR–US Protocol, above note 29, Article II.

34 For a critical assessment, see Pedrozo, Pete, “The U.S.-China Incidents at Sea Agreement: A Recipe for Disaster”, Journal of National Security Law and Policy, Vol. 6, No. 1, 2012Google Scholar.

35 In the maritime context, the rules of the road are laid down in the International Regulations for Preventing Collisions at Sea.

36 US–USSR Agreement, above note 29, Article III(1) and (2).

37 Ibid., Article III(4).

38 ICRC Commentary on GC II, para. 263.

39 Ibid., para. 249.

40 Article 30 of UNCLOS provides: “If any warship does not comply with the laws and regulations of the coastal State concerning passage through the territorial sea and disregards any request for compliance therewith which is made to it, the coastal State may require it to leave the territorial sea immediately.”

41 For an assessment of the presence of foreign submarines in the territorial sea, see Kraska, James, “Putting Your Head in the Tiger's Mouth: Submarine Espionage in Territorial Waters”, Columbia Journal of Transnational Law, Vol. 54, No. 1, 2015Google Scholar, available at: http://jtl.columbia.edu/putting-your-head-in-the-tigers-mouth-submarine-espionage-in-territorial-waters/.

42 See ICRC Commentary on GC II, para. 245: “[…] an unconsented-to invasion or deployment of a State’s armed forces on the territory of another State – even if it does not meet with armed resistance – could constitute a unilateral and hostile use of force by one State against another, meeting the conditions for an international armed conflict under Article 2(1).”

43 UNCLOS, Art. 2.

44 Ibid., Art. 38.

45 Ibid., Art. 34(1).

46 Any activity of a foreign warship which is not in compliance with Article 19 of UNCLOS would not constitute a violation of the territorial sovereignty of the coastal State, but would merely entail the coastal State's right under Article 30 of UNCLOS to require the vessel to leave the territorial sea immediately. In other words, the territorial sovereignty is ab initio limited by the right of passage, including non-innocent passage. In case of non-innocent passage, the only remedy available to the coastal State is the right to require the warship to leave the territorial sea immediately.

47 The USS Pueblo is therefore also known as AGER-2.

48 Court of Inquiry to Inquire into the Circumstances relating to the Seizure of the USS Pueblo (AGER-2) by North Korean Naval Forces, which Occurred in the Sea of Japan on 23 January 1968, and the Subsequent Detention of the Vessel and the Officers and Crew, Summary Report, 9 April 1969 (Pueblo Report), p. 34, available at: www.jag.navy.mil/library/investigations/pueblo%20basic%20pt%202.pdf.

49 The secondary mission and mission objectives of USS Pueblo are laid down in a formerly secret but now declassified document (DOCID: 4121723).

50 Pueblo Report, above note 48, p. 36.

51 See US Department of State, telegram, 8 February 1968, reproduced in “Contemporary Practice of the United States Relating to International Law”, American Journal of International Law, Vol. 62, No. 3, 1968, pp. 756–757Google Scholar.

52 Ibid.

53 The document is reprinted in American Journal of International Law, Vol. 63, No. 3, 1969, pp. 684–685.

54 See UN Department of the Law of the Sea, Law of the Sea Bulletin, No. 15, May 1990, p. 29. Claims in (1960) and in 1969: 3 nm: (22) 28; 4 nm: 3; 6 nm: (10) 13; 9 nm: 1; 10 nm: 1; 12 nm: (13) 42; 130 nm: 1; 200 nm: (1) 5. The mere fact that between 1960 and 1969 the number of claims to a 12 nm territorial sea increased from thirteen to forty-two is not sufficient evidence of a general State practice because during the same period, claims to a 3 nm territorial sea increased from twenty-two to twenty-eight. Accordingly, it is safe to conclude that a 3 nm territorial sea, as recognized by the United States in 1968, was considered as being in accordance with customary international law, whereas claims to a 12 nm territorial sea or beyond were not (yet) generally recognized.

55 ICRC Commentary on GC II, para. 246.

56 Ibid., para. 249.

57 See, for instance, the Protocol of 2005 to the Convention for the Suppression of Unlawful Acts Against the Safety of Maritime Navigation, UN Doc. LEG/CONF.15/21, 1 November 2005; UN Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances, UN Doc. E/CONF.82/16, 20 December 1988, reprinted in International Legal Materials, Vol. 28, No. 2, 1989.

58 See Rob McLaughlin, “Law Enforcement at Sea: The Applicable Legal Framework”, in this issue of the Review.

59 UNCLOS, Art. 33.

60 Ibid., Art. 60.

61 Ibid., Art. 73.

62 For a comprehensive analysis, see Papastavridis, Efthymios, The Interception of Vessels on the High Seas: Contemporary Challenges to the Legal Order of the Oceans, Hart, Oxford and Portland, OR, 2014Google Scholar; Guilfoyle, Douglas, Shipping Interdiction and the Law of the Sea, Cambridge University Press, Cambridge, 2009CrossRefGoogle Scholar.

63 For a disproportionate use of force see, inter alia, International Tribunal for the Law of the Sea, The M/V “SAIGA” (No. 2) Case (Saint Vincent and the Grenadines v. Guinea), Judgment, 1 July 1999, para. 155: “use of force must be avoided as far as possible and, where force is unavoidable, it must not go beyond what is reasonable and necessary in the circumstances. Considerations of humanity must apply in the law of the sea, as they do in other areas of international law.”

64 For a similar but more cautious approach, see ICRC Commentary on GC II, para. 249: “In the naval context, under international law applicable at sea, States may, in certain circumstances, lawfully use force against a vessel owned or operated by another State, or registered therein. This may be the case, for example, when coast guards, suspecting a violation of their State's fisheries legislation, attempt to board such a vessel but meet with resistance. The use of force in the course of this and other types of maritime law enforcement operations is regulated by legal notions akin to those regulating the use of force under human rights law. In principle, such measures do not constitute an international armed conflict between the States affiliated with the vessels, in particular where the force is exercised against a private vessel. It cannot be excluded, however, that the use of force at sea is motivated by something other than a State's authority to enforce a regulatory regime applicable at sea. Depending on the circumstances, such a situation may qualify as an international armed conflict.”

65 Although it exclusively defines a jus ad bellum concept, it may be recalled that “an attack by the armed forces of a State on the … marine and air fleets of another State” is considered an “act of aggression”. See Article 3(d) of the Definition of Aggression annexed to UNGA Res. 3314 (XXIX), UN Doc. A/RES/29/3314, 14 December 1974.

66 ICRC Commentary on GC II, para. 249.

67 See Doswald-Beck, Louise (ed.), San Remo Manual on International Law Applicable to Armed Conflicts at Sea, Cambridge University Press, Cambridge, 1995CrossRefGoogle Scholar, Part V, paras 112–158; HPCR Manual, above note 9, Section U (Rules 134–146).

68 See Dan Parsons, “South China Sea Dispute Shaping Up as Coast Guard Showdown”, National Defense Magazine, June 2014, available at: www.nationaldefensemagazine.org/articles/2014/6/1/2014june-south-china-sea-dispute-shaping-up-as-coast-guard-showdown; Bonnie S. Glaser, “Conflict in the South China Sea”, Council on Foreign Relations, Contingency Planning Memorandum Update, 7 April 2015, available at: www.cfr.org/report/conflict-south-china-sea; “China's Coast Guard Cause Most South China Sea Clashes, US Report Finds”, CNBC, 6 September 2016, available at: www.cnbc.com/2016/09/06/chinas-coast-guard-cause-most-south-china-sea-clashes-us-report-finds.html. See also Kraska, James and Monti, Michael, “The Law of Naval Warfare and China's Maritime Militia”, International Law Studies, Vol. 91, 2015Google Scholar, available at: http://stockton.usnwc.edu/ils/vol91/iss1/13/.

69 ICRC Commentary on GC II, para. 248.