Who Still Believes in Article 2(4)? The Strategic Expansion of Self-Defence and the Case for Institutional Reform of the Law on Force
Keywords:
jus ad bellum, humanitarian intervention, non-state actors, self-defence, use of force, UN CharterAbstract
The prohibition on the use of force enshrined in Article 2(4) of the UN Charter was intended to serve as the focal point of the post-1945 international order. Eighty years on, that prohibition is under more pressure than at any point since the Cold War. This paper argues that the contemporary crisis surrounding the prohibition on force is not one of textual ambiguity but of strategic instrumentalisation: states are not rejecting the norm against force so much as hollowing it out through expansive reinterpretation of its exceptions, including the right to self-defence under Article 51, increasingly invoked humanitarian intervention, and pre-emptive actions against non-state actors. Drawing on a theoretical framework that integrates constructivist norm life-cycle theory by Finnemore & Sikkink with the critical legal realism of Koskenniemi, the paper examines how state practice since 2001 has progressively widened the self-defence exception to the point where it risks swallowing the rule. It traces this trajectory through four contemporary flashpoints: the extraterritorial use of force against non-state armed groups; US and allied operations in Syria post-2014; Russia’s invocation of protective intervention in Ukraine (2014–2022); and the emerging discourse around anticipatory self-defence in the context of cyber operations and AI-enabled weapons systems. The paper concludes that the current normative framework is not broken but is being selectively enforced in ways that entrench power asymmetries. Meaningful reform requires a reinvigoration of the institutional framework, including a formalised General Assembly override mechanism for Security Council vetoes on matters involving jus ad bellum disputes.
References
1. Charter of the United Nations 1945, art 2(4); Ian Brownlie, International Law and the Use of Force by States (OUP 1963) 112–114; Christine Gray, International Law and the Use of Force (4th edn, OUP 2018) 6–30.
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3. Letter dated 23 September 2014 from the Permanent Representative of the United States of America to the United Nations addressed to the Secretary-General, UN Doc S/2014/695 accessed 29 March 2026; See also Ashley Deeks, '"Unwilling or Unable": Toward a Normative Framework for Extraterritorial Self-Defense' (2012) 52 Virginia Journal of International Law 483.
4. Thomas Franck, ‘Who Killed Article 2(4)?’ (1970) 64 (5) AJIL 809-837; Louis Henkin, ‘The Reports of the Death of Article 2(4) Are Greatly Exaggerated’ (1971) 65 AJIL 544.
5. Martha Finnemore and Kathryn Sikkink, ‘International Norm Dynamics and Political Change’ (1998) 52 International Organization 887, 895–905; Diana Panke and Ulrich Petersohn, ‘Why International Norms Disappear Sometimes’ (2012) 18 European Journal of International Relations 719.
6. Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America) (Merits) [1986] ICJ Rep 14 [176]–[179].
7. Charter of the United Nations, art 27(3) (requiring the ‘concurring votes of the permanent members’ for non-procedural decisions). For a comprehensive record of vetoes cast since 1946, see UN Dag Hammarskjöld Library, ‘Security Council – Veto List’ <https://research.un.org/en/docs/sc/quick> accessed 29 March 2026. On the structural consequences for collective security, see Jan Wouters and Tom Ruys, ‘Security Council Reform: A New Veto for a New Century?’ (Egmont Institute, Royal Institute for International Relations 2005) <https://aei.pitt.edu/8980/1/ep9.pdf> accessed 29 March 2026; Michael J Kelly, ‘United Nations Security Council Permanent Membership and the Veto Problem’ (2020) 52 Case Western Reserve Journal of International Law 101 <https://scholarlycommons.law.case.edu/jil/vol52/iss1/8/> accessed 29 March 2026.
8. UNSC Res 1368 (12 September 2001) UN Doc S/RES/1368; Ashley Deeks, ‘“Unwilling or Unable”: Toward a Normative Framework for Extraterritorial Self-Defense’ (2012) 52 Virginia Journal of International Law 483; Letter dated 23 September 2014 from the Permanent Representative of the United States to the Secretary-General, UN Doc S/2014/695 available here <https://www.securitycouncilreport.org/atf/cf/%7B65BvFCF9B-6D27-4E9C-8CD3-CF6E4FF96FF9%7D/s_2014_695.pdf>; Noam Lubell, Extraterritorial Use of Force Against Non-State Actors (OUP 2010) 25–55.
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11. Olivier Corten, The Law Against War (Hart 2010) 163–196; Yoram Dinstein, War, Aggression and Self-Defence (6th edn, CUP 2017) 192–203.
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14. OAS Permanent Council, ‘Convocation of the Meeting of Consultation of Ministers of Foreign Affairs and Appointment of a Commission’ CP/RES 930 (1632/08) (5 March 2008) (reaffirming the principle of territorial inviolability following Colombia’s 1 March 2008 strike against a FARC encampment in Ecuadorian territory). Colombia apologised and undertook not to repeat the operation, and the episode generated no wider pattern of endorsement in the region.
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17. Ian Brownlie, International Law and the Use of Force by States (OUP 1963) 265–268. Brownlie’s account remains the foundational positivist treatment, reading the prohibition as near-absolute.
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21. Charter of the United Nations, art 39: ‘The Security Council shall determine the existence of any threat to the peace, breach of the peace, or act of aggression and shall make recommendations, or decide what measures shall be taken in accordance with Articles 41 and 42, to maintain or restore international peace and security.’; Charter of the United Nations, art 42: ‘Should the Security Council consider that measures provided for in Article 41 would be inadequate or have proved to be inadequate, it may take such action by air, sea, or land forces as may be necessary to maintain or restore international peace and security.’
22. Charter of the United Nations, art 51: ‘Nothing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken the measures necessary to maintain international peace and security.’
23. Christine Gray, International Law and the Use of Force (4th edn, OUP 2018) 6–30, 117–160.
24. Charter of the United Nations, art 27(3). For a comprehensive record of vetoes cast, see UN Dag Hammarskjöld Library, ‘Security Council – Veto List’ <https://research.un.org/en/docs/sc/quick> accessed 29 March 2026.
25. Jan Wouters and Tom Ruys, ‘Security Council Reform: A New Veto for a New Century?’ (Egmont Institute 2005) <https://aei.pitt.edu/8980/1/ep9.pdf> accessed 29 March 2026; Michael J Kelly, ‘United Nations Security Council Permanent Membership and the Veto Problem’ (2020) 52 Case Western Reserve Journal of International Law 101 <https://scholarlycommons.law.case.edu/jil/vol52/iss1/8/> accessed 29 March 2026.
26. UNGA Res 377(V) (3 November 1950) UN Doc A/RES/377(V) (‘Uniting for Peace’).
27. Martti Koskenniemi, From Apology to Utopia: The Structure of International Legal Argument (CUP 2005) 58–70.
28. Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America) (Merits) [1986] ICJ Rep 14 <https://www.icj-cij.org/case/70> accessed 29 March 2026.
29. ibid [176]–[179]
30. ibid [191]–[195] (distinguishing ‘armed attack’ from lesser forms of force, including provision of weapons and logistical support to insurgents; holding that the latter, while potentially unlawful, does not trigger the right of self-defence).
31. ibid [194]–[196]
32. ibid [237]–[238]
33. UNSC Draft Resolution S/18428 (28 October 1986), vetoed by the United States (11 votes in favour, 1 against; France, Thailand and the United Kingdom abstaining), UN Doc S/PV.2704 (1986). See also UNGA Res 41/31 (3 November 1986) (calling for full and immediate compliance with the judgment, adopted 94 to 3).
34. Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America) (Merits) [1986] ICJ Rep 14 [176]–[195], [237]–[238] <https://www.icj-cij.org/case/70> accessed 29 March 2026.
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36. Allegations of Genocide under the Convention on the Prevention and Punishment of the Crime of Genocide (Ukraine v Russian Federation) (Provisional Measures) [2022] ICJ Rep 211 [59]–[60] <https://www.icj-cij.org/case/182> accessed 13 June 2026.
37. Andrew T. Guzman, How International Law Works: A Rational Choice Theory (OUP 2008) 33–48.
38. Legality of the Threat or Use of Nuclear Weapons (Advisory Opinion) [1996] ICJ Rep 226 [38]–[48] <https://www.icj-cij.org/case/95> accessed 29 March 2026.
39. ibid (‘the Court cannot conclude definitively whether the threat or use of nuclear weapons would be lawful or unlawful in an extreme circumstance of self-defence, in which the very survival of a State would be at stake’).
40. Koskenniemi (n 27) 58–70. The Court’s non liquet in Nuclear Weapons is perhaps the purest illustration of his thesis: the legal arguments for and against were perfectly balanced, and the Court resolved the impasse by declining to resolve it.
41. Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory (Advisory Opinion) [2004] ICJ Rep 136 [139].
42. ibid, Declaration of Judge Buergenthal [5]–[6] (describing the majority’s reasoning as a ‘formalistic approach’ resting on a ‘legally dubious conclusion’); Separate Opinion of Judge Higgins [33]–[34]; Separate Opinion of Judge Kooijmans [35].
43. Sean D Murphy, ‘Self-Defense and the Israeli Wall Advisory Opinion: An Ipse Dixit from the ICJ?’ (2005) 99 AJIL 62, 64.
44. Armed Activities on the Territory of the Congo (Democratic Republic of the Congo v Uganda) (Merits) [2005] ICJ Rep 168, Separate Opinion of Judge Kooijmans [25]–[32]; Separate Opinion of Judge Simma [8]–[15].
45. Armed Activities on the Territory of the Congo (Democratic Republic of the Congo v Uganda) (Merits) [2005] ICJ Rep 168 <https://www.icj-cij.org/case/116> accessed 29 March 2026.
46. ibid [146]–[147] (holding that Uganda’s military intervention could not be justified as self-defence because the DRC’s actions did not constitute an ‘armed attack’ within the meaning of Article 51).
47. ibid, Judge Kooijmans, Separate Opinion [25]–[32]; Judge Simma, Separate Opinion [8]–[15]. Both endorsed the possibility of self-defence against non-state actors operating from a host state’s territory where that state is unable or unwilling to suppress the threat.
48. Diana Panke and Ulrich Petersohn, ‘Why International Norms Disappear Sometimes’ (2012) 18 European Journal of International Relations 719, 723–728; Finnemore and Sikkink (n 5) 895–898 (describing the three-stage lifecycle: norm emergence, norm cascade, and internalisation). The prohibition on force reached ‘internalisation’ after 1945 but the post-2001 period exhibits the characteristics of what Panke and Petersohn term ‘norm regression’.
49. Tom Ruys, ‘Armed Attack’ and Article 51 of the UN Charter (CUP 2010) 485–530 <https://doi.org/10.1017/CBO9780511779527> accessed 29 March 2026; Yoram Dinstein, War, Aggression and Self-Defence (6th edn, CUP 2017) 192–203.
50. Koskenniemi (n 27) 17–18. The structural indeterminacy is not a defect in the law; it is a constitutive feature of an international legal order that lacks compulsory adjudication and centralised enforcement.
51. Letter dated 23 September 2014 from the Permanent Representative of the United States of America to the United Nations addressed to the Secretary-General, UN Doc S/2014/695 <https://www.securitycouncilreport.org/atf/cf/%7B65BFCF9B-6D27-4E9C-8CD3-CF6E4FF96FF9%7D/s_2014_695.pdf> accessed 29 March 2026.
52. Ashley Deeks, ‘“Unwilling or Unable”: Toward a Normative Framework for Extraterritorial Self-Defense’ (2012) 52 Virginia Journal of International Law 483; Noam Lubell, Extraterritorial Use of Force Against Non-State Actors (OUP 2010) 25–55.
53. Letter dated 25 November 2014 from the Permanent Representative of the United Kingdom to the President of the Security Council, UN Doc S/2014/851 (citing collective self-defence of Iraq). See also Ashley Deeks, ‘The UK’s Article 51 Letter on Use of Force in Syria’ (Lawfare, 26 November 2014) <https://www.lawfaremedia.org/article/uks-article-51-letter-use-force-syria> accessed 29 March 2026.
54. Letter dated 8 September 2015 from the Permanent Representative of France to the President of the Security Council, UN Doc S/2015/745 (invoking individual self-defence following the Paris attacks of 13 November 2015 and UNSC Res 2249 (20 November 2015) UN Doc S/RES/2249).
55. Letter dated 31 March 2015 from the Chargé d’Affaires of the Permanent Mission of Canada to the President of the Security Council, UN Doc S/2015/221 (expressly invoking the ‘unable or unwilling’ formulation); Letter dated 9 September 2015 from the Permanent Representative of Australia to the President of the Security Council, UN Doc S/2015/693.
56. Olivier Corten, ‘The “Unwilling or Unable” Test: Has It Been, and Could It Be, Accepted?’ (2016) 29 Leiden Journal of International Law 777.
57. Identical letters dated 21 September 2015 from the Permanent Representative of the Syrian Arab Republic to the Secretary-General and the President of the Security Council, UN Doc A/70/385–S/2015/727 (protesting that the coalition strikes ‘distort the provisions of the Charter and manipulate international law’).
58. Tom Ruys, ‘Armed Attack’ and Article 51 of the UN Charter (CUP 2010) 485–530 <https://doi.org/10.1017/CBO9780511779527> accessed 29 March 2026.
59. Diana Panke and Ulrich Petersohn, ‘Why International Norms Disappear Sometimes’ (2012) 18 European Journal of International Relations 719, 725–728 (describing ‘norm entrepreneurs’ who advance competing interpretations that fragment consensus without formally rejecting the underlying norm).
60. Martha Finnemore and Kathryn Sikkink, ‘International Norm Dynamics and Political Change’ (1998) 52 International Organization 900–905.
61. Letter dated 24 February 2022 from the Permanent Representative of the Russian Federation to the United Nations addressed to the Secretary-General, UN Doc S/2022/154 <https://digitallibrary.un.org/record/3959647> accessed 29 March 2026; Marko Milanovic, ‘What is Russia’s Legal Justification for Using Force against Ukraine?’ (EJIL: Talk!, 24 February 2022) <https://www.ejiltalk.org/what-is-russias-legal-justification-for-using-force-against-ukraine/> accessed 29 March 2026.
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65. Bruno Simma, 'NATO, the UN and the Use of Force: Legal Aspects' (1999) 10 European Journal of International Law 1. On the UK's legal position, see Foreign Affairs Committee, 'Kosovo' (HC 1999–2000, 28) Memorandum by the Foreign and Commonwealth Office <https://publications.parliament.uk/pa/cm199900/cmselect/cmfaff/28/0020802.htm> accessed 29 March 2026 (articulating a doctrine of humanitarian intervention as 'an exceptional measure to prevent an overwhelming humanitarian catastrophe').
66. Olivier Corten, The Law Against War (Hart 2010) 497–544 <https://doi.org/10.5040/9781472565662> accessed 29 March 2026. See also Letter dated 20 March 2003 from the Permanent Representative of the United States to the President of the Security Council, UN Doc S/2003/351 (invoking UNSC Resolutions 678 (1990) and 687 (1991) as authorisation for the use of force)
67. UNSC Res 1973 (17 March 2011) UN Doc S/RES/1973 (authorising member states to take 'all necessary measures' to protect civilians in Libya). On the subsequent controversy over the scope of the mandate, see Christine Gray, International Law and the Use of Force (4th edn, OUP 2018) 37–44.
68. Olivier Corten, The Law Against War (Hart, 2010) 497–544; Letter dated 20 March 2003 from the Permanent Representative of the United States to the President of the Security Council, UN Doc S/2003/351; Letter dated 20 March 2003 from the Permanent Representative of the United Kingdom, UN Doc S/2003/350 (both invoking UNSC Resolutions 678 (1990) and 687 (1991) as authorisation)
69. UNSC Res 1973 (17 March 2011) UN Doc S/RES/1973 (authorising 'all necessary measures' to protect civilians). On the mandate's expansion into regime change, see Christine Gray, International Law and the Use of Force (4th edn, OUP 2018) 37–44
70. James A Green, Christian Henderson and Tom Ruys, 'Russia's Attack on Ukraine and the Jus ad Bellum' (2022) 9 Journal on the Use of Force and International Law 8–12
71. Martti Koskenniemi, From Apology to Utopia: The Structure of International Legal Argument (CUP 2005) 58–70.
72. Koskenniemi (n 27) 17–18.
73. Panke and Petersohn (n 59) 730–733 (arguing that norm erosion accelerates when competing interpretations are advanced by multiple powerful actors rather than a single outlier); Finnemore and Sikkink (n 54) 902–904 (observing that norms are most vulnerable when the behaviour of norm-violators can be framed as consistent with the norm itself, because this prevents the clear ‘naming and shaming’ that sustains compliance).
74. Michael N Schmitt (ed), Tallinn Manual 2.0 on the International Law Applicable to Cyber Operations (CUP 2017) Rules 69–71, pp 329-354; Marco Roscini, Cyber Operations and the Use of Force in International Law (OUP 2014) 43–74.
75. Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America) (Merits) [1986] ICJ Rep 14 [191]–[195]; Tallinn Manual 2.0 (n 1) Rule 71, commentary [6]–[13], adopting a ‘scale and effects’ analysis, under which a cyber operation constitutes a use of force when its consequences are analogous to those of a kinetic operation that would qualify as such.
76. See the NotPetya attack (2017), attributed to Russia’s GRU, which caused an estimated USD 10 billion in global economic damage without producing kinetic destruction; The White House, 'Statement from the Press Secretary' (15 February 2018) (attributing NotPetya to the Russian military and describing it as 'the most destructive and costly cyber-attack in history') https://trumpwhitehouse.archives.gov/briefings-statements/statement-press-secretary-25/ accessed 29 March 2026; UK Foreign Office, 'Foreign Office Minister Condemns Russia for NotPetya Attacks' (15 February 2018) https://www.gov.uk/government/news/foreign-office-minister-condemns-russia-for-notpetya-attacks accessed 29 March 2026; Andy Greenberg, 'The Untold Story of NotPetya, the Most Devastating Cyberattack in History' (Wired, 22 August 2018) https://www.wired.com/story/notpetya-cyberattack-ukraine-russia-code-crashed-the-world/ accessed 29 March 2026.
77. Andy Greenberg, 'The Untold Story of NotPetya, the Most Devastating Cyberattack in History' (Wired, 22 August 2018) <https://www.wired.com/story/notpetya-cyberattack-ukraine-russia-code-crashed-the-world/> accessed 29 March 2026.
78. Michael N Schmitt, 'Grey Zones in the International Law of Cyberspace' (2017) 42 Yale Journal of International Law Online 1, 4–8 (analysing why state practice has consistently declined to characterise major cyber operations as armed attacks or uses of force, notwithstanding their scale and effects).
79. The White House, 'Statement from the Press Secretary' (15 February 2018) <https://trumpwhitehouse.archives.gov/briefings-statements/statement-press-secretary-25/> accessed 29 March 2026 (attributing NotPetya to the Russian military); UK Foreign Office, 'Foreign Office Minister Condemns Russia for NotPetya Attacks' (15 February 2018) <https://www.gov.uk/government/news/foreign-office-minister-condemns-russia-for-notpetya-attacks> accessed 29 March 2026. The coordinated attribution by the US, UK, Canada, Australia, and several EU member states was accompanied by limited sanctions but no invocation of the jus ad bellum framework.
80. Marco Roscini, Cyber Operations and the Use of Force in International Law (OUP 2014) 43–74; Michael N Schmitt (ed), Tallinn Manual 2.0 on the International Law Applicable to Cyber Operations (CUP 2017) Rule 69, commentary [1]–[9] <https://doi.org/10.1017/9781316822524> accessed 29 March 2026 (acknowledging that the effects-based threshold leaves substantial operations in a doctrinal grey zone where classification depends on state discretion rather than objective criteria).
81. Kim Zetter, Countdown to Zero Day: Stuxnet and the Launch of the World's First Digital Weapon (Crown 2014); David E Sanger, 'Obama Order Sped Up Wave of Cyberattacks Against Iran' (New York Times, 1 June 2012) <https://www.nytimes.com/2012/06/01/world/middleeast/obama-ordered-wave-of-cyberattacks-against-iran.html> accessed 29 March 2026.
82. Institute for Science and International Security, 'Stuxnet Malware and Natanz: Update of ISIS December 22, 2010 Report' (15 February 2011) <https://isis-online.org/isis-reports/detail/stuxnet-malware-and-natanz-update-of-isis-december-22-2010-reportsupa-markup> accessed 29 March 2026.
83. Michael N Schmitt (ed), Tallinn Manual 2.0 on the International Law Applicable to Cyber Operations (CUP 2017) Rule 69, commentary [1]–[9], Rule 71 commentary [6]–[13] <https://doi.org/10.1017/9781316822524> accessed 29 March 2026.
84. Marco Roscini, Cyber Operations and the Use of Force in International Law (OUP 2014) 55–62 (analysing Iran's non-response as evidence that jus ad bellum characterisation in the cyber domain is driven by political interest rather than doctrinal assessment).
85. International Committee of the Red Cross, 'Autonomous Weapon Systems: Technical, Military, Legal and Humanitarian Aspects' (Expert Meeting, Geneva, 26–28 March 2014); UNGA, 'Lethal Autonomous Weapons Systems', Report of the Secretary-General, UN Doc A/78/324 (2023).
86. Marco Roscini, 'Assessing the Role of AI in Determining the Necessity and Proportionality of the Exercise of Self-Defense against an Armed Attack' (2025) 107 International Law Studies 76.
87. Yuval Abraham, '"Lavender": The AI Machine Directing Israel's Bombing Spree in Gaza' (+972 Magazine, 3 April 2024) < ‘Lavender’: The AI machine directing Israel’s bombing spree in Gaza> accessed 29 March 2026 (reporting that the Israeli military's AI-assisted system generated targeting recommendations with an average human review time of approximately 20 seconds per target).
88. On the Aegis Combat System's autonomous engagement capability, see US Department of Defense, 'Autonomy in Weapon Systems' (Directive 3000.09, updated 25 January 2023); Paul Scharre, Army of None: Autonomous Weapons and the Future of War (WW Norton 2018) 9–31.
89. See ICRC, 'Position on Autonomous Weapon Systems' (12 May 2021) accessed 29 March 2026; Convention on Certain Conventional Weapons, Group of Governmental Experts on Emerging Technologies in the Area of Lethal Autonomous Weapons Systems, Reports of Sessions (2017–2023).
90. Koskenniemi's framework suggests that law requiring deliberation cannot survive the elimination of the deliberative actor. The indeterminacy is no longer interpretive; it is temporal. See Martti Koskenniemi, From Apology to Utopia: The Structure of International Legal Argument (CUP 2005) 58–70.
91. Marco Roscini, 'Assessing the Role of AI in Determining the Necessity and Proportionality of the Exercise of Self-Defense against an Armed Attack' (2025) 107 International Law Studies 76, 89–95. See also Dustin A Lewis, Gabriella Blum and Naz K Modirzadeh, War-Algorithm Accountability (Research Briefing, Harvard Law School Program on International Law and Armed Conflict, August 2016) 28–36.
92. International Committee of the Red Cross, 'Autonomous Weapon Systems: Technical, Military, Legal and Humanitarian Aspects' (Expert Meeting, Geneva, 26–28 March 2014) 65–67; UNGA, 'Lethal Autonomous Weapons Systems', Report of the Secretary-General, UN Doc A/78/324 (2023) paras 31–38.
93. The analogy is imperfect because domestic due process rights attach to individuals, whereas jus ad bellum requirements attach to states. The structural point nonetheless holds: both regimes impose procedural expectations that are not satisfied merely by the correctness of the outcome. On the procedural dimensions of jus ad bellum compliance more broadly, see Jutta Brunnée and Stephen J. Toope, Legitimacy and Legality in International Law: An Interactional Account (CUP 2010) 265–290.
94. Aerial Incident of 3 July 1988 (Islamic Republic of Iran v United States of America), discontinued by Order of 22 February 1996 [1996] ICJ Rep 9. For the factual record, see US Department of Defense, 'Formal Investigation into the Circumstances Surrounding the Downing of Iran Air Flight 655 on 3 July 1988' (Investigation Report, 28 July 1988) (the Fogarty Report).
95. Paul Scharre, Army of None: Autonomous Weapons and the Future of War (WW Norton 2018) 231–258. The Fogarty Report concluded that the crew's situational awareness degraded under combat stress in ways that the automated tracking system neither detected nor compensated for; the operators trusted the system's classification even as it diverged from available radar data.
96. Judith Gardam, Necessity, Proportionality and the Use of Force by States (CUP 2004) 156–162.
97. Protocol Additional to the Geneva Conventions of 12 August 1949 and Relating to the Protection of Victims of International Armed Conflicts (Protocol I) (adopted 8 June 1977, entered into force 7 December 1978) 1125 UNTS 3, art 51(5)(b).
98. Oil Platforms (Islamic Republic of Iran v United States of America) (Merits) [2003] ICJ Rep 161 [43], [76]. See also Yoram Dinstein, War, Aggression and Self-Defence (6th edn, CUP 2017) 262–268
99. RY Jennings, 'The Caroline and McLeod Cases' (1938) 32 American Journal of International Law 82, 89.
100. Yoram Dinstein, War, Aggression and Self-Defence (6th edn, CUP 2017) 203–210; Christine Gray, International Law and the Use of Force (4th edn, OUP 2018) 160–175.
101. Letter dated 8 January 2020 from the Permanent Representative of the United States to the President of the Security Council, UN Doc S/2020/20 (invoking self-defence under Article 51). On the contested imminence claim, see Agnes Callamard, 'The Targeted Killing of General Soleimani: Its Lawfulness and Why It Matters' (Just Security 8 January 20220 (concluding that the evidence disclosed did not satisfy the imminence requirement under international law)
102. Andy Greenberg, Sandworm: A New Era of Cyberwar and the Hunt for the Kremlin's Most Dangerous Hackers (Doubleday 2019) 55–78 (documenting the 2015 and 2016 Russian GRU cyberattacks on Ukraine's electrical grid, which caused widespread blackouts affecting approximately 230,000 people). Michael N Schmitt (ed), Tallinn Manual 2.0 on the International Law Applicable to Cyber Operations (CUP 2017) Rule 73, commentary [2]–[4] <https://doi.org/10.1017/9781316822524> accessed 29 March 2026 (noting that the majority of experts accepted the extension of anticipatory self-defence to cyber operations where an armed attack is imminent, while acknowledging disagreement on the threshold).
103. The White House, The National Security Strategy of the United States of America (September 2002) 15 (asserting that the US would 'act against such emerging threats before they are fully formed'). On its rejection, see Olivier Corten, The Law Against War (Hart 2010) 406–441; Christine Gray (n 100) 230–240.
104. Martha Finnemore and Kathryn Sikkink, 'International Norm Dynamics and Political Change' (1998) 52 International Organization 887, 900–905; Diana Panke and Ulrich Petersohn, 'Why International Norms Disappear Sometimes' (2012) 18 European Journal of International Relations 719, 733–735
105. Between 2011 and 2024, Russia cast sixteen vetoes on Syria-related resolutions, shielding the Assad regime from collective enforcement action throughout a conflict that produced over 500,000 deaths and displaced 13 million people.
106. UNSC Draft Resolution S/18428 (28 October 1986), vetoed by the United States, UN Doc S/PV.2704 (calling for compliance with the ICJ judgment in Nicaragua v United States). On Gaza, see UNSC Draft Resolution S/2023/970 (18 October 2023), vetoed by the United States; UNSC Draft Resolution S/2024/173 (20 February 2024), vetoed by the United States.
107. Martti Koskenniemi, From Apology to Utopia: The Structure of International Legal Argument (CUP 2005) 58–70.
108. Statute of the International Court of Justice, art 36(2) (the 'Optional Clause'). As of 2025, only 73 of 193 UN member states have accepted compulsory jurisdiction.
109. The United States withdrew its acceptance of compulsory jurisdiction on 7 October 1985, effective 7 April 1986, in direct response to the Nicaragua proceedings. See US Department of State, 'US Withdrawal from the Proceedings Initiated by Nicaragua in the International Court of Justice' (1985) 24 ILM 246. Russia (and its predecessor the Soviet Union) has never filed a declaration under the Optional Clause.
110. Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America) (Merits) [1986] ICJ Rep 14; UNSC Draft Resolution S/18428 (28 October 1986), vetoed by the United States, UN Doc S/PV.2704. Armed Activities on the Territory of the Congo (DRC v Uganda) (Merits) [2005] ICJ Rep 168; (Reparations) [2022] ICJ Rep 13 <https://www.icj-cij.org/case/116> accessed 29 March 2026 (the Court fixed the amount of reparation at USD 325 million,seventeen years after the merits judgment).
111. Allegations of Genocide under the Convention on the Prevention and Punishment of the Crime of Genocide (Ukraine v Russian Federation) (Provisional Measures) [2022] ICJ Rep 211 <https://www.icj-cij.org/case/182> accessed 29 March 2026.
112. Martha Finnemore and Kathryn Sikkink, 'International Norm Dynamics and Political Change' (1998) 52 International Organisation 900–905; Diana Panke and Ulrich Petersohn, 'Why International Norms Disappear Sometimes' (2012) 18 European Journal of International Relations 719, 733–735.
113. UNGA Res ES-11/1 (2 March 2022) UN Doc A/RES/ES-11/1 <https://digitallibrary.un.org/record/3965290> accessed 29 March 2026.
114. Martti Koskenniemi, From Apology to Utopia: The Structure of International Legal Argument (CUP 2005) 58–70.
115. Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America) (Merits) [1986] ICJ Rep 14 [176]–[195]. On the law-clarifying function of international adjudication independent of compliance, see Yuval Shany, 'Assessing the Effectiveness of International Courts: A Goal-Based Approach' (2012) 106 AJIL 225, 253–258.
116. Allegations of Genocide under the Convention on the Prevention and Punishment of the Crime of Genocide (Ukraine v Russian Federation) (Provisional Measures) [2022] ICJ Rep 211 [59]–[60] <https://www.icj-cij.org/case/182> accessed 29 March 2026. The Court's jurisdiction rested solely on the compromissory clause in art IX of the Genocide Convention, which does not extend to the lawfulness of the resort to force as such.
117. On reputation as a mechanism of compliance in the absence of coercive enforcement, see Andrew T Guzman, How International Law Works: A Rational Choice Theory (OUP 2008) 33–48.
118. Charter of the United Nations, art 108 (requiring ratification by two-thirds of UN members, including all P5 members). The P5 veto over Charter amendment is the structural reason why the proposals here are framed as institutional innovations within the existing framework.
119. UNGA Res 377(V) (3 November 1950) UN Doc A/RES/377(V) ('Uniting for Peace') https://digitallibrary.un.org/record/210079 accessed 29 March 2026. UNGA Res 377(V) (3 November 1950) UN Doc A/RES/377(V) ('Uniting for Peace'). The resolution was invoked to convene the eleventh emergency special session on Ukraine in February 2022, but the resulting resolutions carried no binding force.
120. The proposal would formalise and extend the Uniting for Peace mechanism by empowering the General Assembly to take enforcement decisions,not merely recommendations, where a two-thirds supermajority determines that a prima facie violation of Article 2(4) has occurred and the Security Council has been prevented from acting by the veto.
121. Statute of the International Court of Justice, art 36(1)–(2).
122. ibid arts 65–68; Shabtai Rosenne, The Law and Practice of the International Court, 1920–2005 (4th edn, Martinus Nijhoff 2006) vol III, 1652–1660.
123. Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory (Advisory Opinion) [2004] ICJ Rep 136 [46]–[50]
124. Legality of the Threat or Use of Nuclear Weapons (Advisory Opinion) [1996] ICJ Rep 226.
125. Eric A Posner and Miguel FP de Figueiredo, ‘Is the International Court of Justice Biased?’ (2005) 34 Journal of Legal Studies 599 (finding statistical evidence that judges favour their home states and states at similar levels of development, while noting the limits of the data).
126. Legality of the Threat or Use of Nuclear Weapons (Advisory Opinion) [1996] ICJ Rep 226 [97]; cf Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America) (Merits) [1986] ICJ Rep 14, a standing counter-example of the Court ruling against a superpower.
127. The regional groups are the African Group, the Asia-Pacific Group, the Eastern European Group, the Latin American and Caribbean Group, and the Western European and Others Group. Cross-regional thresholds are familiar from the Assembly’s practice of equitable geographical distribution, including under art 23(1) of the UN Charter.
128. UNGA Res ES-11/1 (2 March 2022) UN Doc A/RES/ES-11/1 (adopted 141 in favour, 5 against, 35 abstentions, a near-unprecedented majority that produced no enforceable consequence).
129. On the politicisation of international commissions of inquiry and the variability of their methods, see Catherine Harwood, The Roles and Functions of Atrocity-Related United Nations Commissions of Inquiry in the International Legal Order: Navigating between Principle and Pragmatism (Brill Nijhoff 2019) ; Larissa van den Herik, 'An Inquiry into the Role of Commissions of Inquiry in International Law: Navigating the Tensions between Fact-Finding and Application of International Law' (2014) 13 Chinese Journal of International Law 507, 518–524.
130. A standing roster appointed by the President of the Court would draw on the model used for the formation of chambers under art 26 of the Statute of the International Court of Justice, insulating panel composition from case-specific political pressure.
131. The right of the affected state to comment before any adverse determination reflects the audi alteram partem principle, recognised as a general principle of law. See Bin Cheng, General Principles of Law as Applied by International Courts and Tribunals (CUP 1953, reprinted 2006) 290–298.
132. Francis M Deng and others, Sovereignty as Responsibility: Conflict Management in Africa (Brookings Institution Press 1996); International Commission on Intervention and State Sovereignty, The Responsibility to Protect (International Development Research Centre 2001) paras 2.14–2.15.
133. UNGA Res 60/1 (24 October 2005) UN Doc A/RES/60/1 paras 138–139 (confining the responsibility to protect to a Security Council response and declining to endorse any unilateral right of intervention).
134. Anne Orford, International Authority and the Responsibility to Protect (CUP 2011) 1–41 (tracing the genealogy of the concept and its contested reception).
135. Dire Tladi, ‘The Nonconsenting Innocent State: The Problem with Bethlehem’s Principle 12’ (2013) 107(3) AJIL 570, 574–575. See also Mary Ellen O’Connell, ‘Dangerous Departures’ (2013) 107 AJIL 380; Elizabeth Wilmshurst and Michael Wood, ‘Self-Defense Against Nonstate Actors: Reflections on the “Bethlehem Principles”’ (2013) 107 AJIL 390; Mahmoud Hmoud, ‘Are New Principles Really Needed?’ (2013) 107 AJIL 576.
136. Olivier Corten, ‘The “Unwilling or Unable” Test: Has It Been, and Could It Be, Accepted?’ (2016) 29 Leiden Journal of International Law 777, 785–793 (documenting rejection of the doctrine by a substantial number of states, including Russia, China, and members of the Non-Aligned Movement); Erika de Wet, ‘The Invocation of the Right to Self-Defence in Response to Armed Attacks Conducted by Armed Groups: Implications for Attribution’ (2019) 32 Leiden Journal of International Law 91.
137. Letter dated 23 September 2014 from the Permanent Representative of the United States, UN Doc S/2014/695; Letter dated 25 November 2014 from the Permanent Representative of the United Kingdom, UN Doc S/2014/851; Letter dated 31 March 2015 from the Permanent Mission of Canada, UN Doc S/2015/221; Letter dated 9 September 2015 from the Permanent Representative of Australia, UN Doc S/2015/693; Letter dated 8 September 2015 from the Permanent Representative of France, UN Doc S/2015/745.
138. Ashley Deeks, '"Unwilling or Unable": Toward a Normative Framework for Extraterritorial Self-Defense' (2012) 52 Virginia Journal of International Law 483, 503–519.
139. Charter of the United Nations, art 51; See Security Council Report, 'In Hindsight: The Increasing Use of Article 51 of the UN Charter and the Security Council' (October 2025).
140. The US invoked collective self-defence with the 'unable or unwilling' formulation; the UK cited collective self-defence of Iraq without the phrase; France invoked individual self-defence; Canada and Australia adopted the 'unable or unwilling' test expressly. No institution has assessed the legality of any of these justifications.
141. Charter of the United Nations, art 108 (amendments enter into force when adopted by a two-thirds vote of the General Assembly and ratified by two-thirds of UN members, including all permanent members of the Security Council). The same constraint governs amendments adopted through a review conference under art 109(2).
142. UNGA Res 377(V) (3 November 1950) GAOR 5th Session Supp 20, 10. On its adoption notwithstanding Soviet opposition and its constitutional significance, see Christian Tomuschat, 'Uniting for Peace' (UN Audiovisual Library of International Law, 2008) https://legal.un.org/avl/ha/ufp/ufp.html accessed 29 March 2026; Dominik Zaum, 'The Security Council, the General Assembly, and War: The Uniting for Peace Resolution' in Vaughan Lowe, Adam Roberts, Jennifer Welsh and Dominik Zaum (eds), The United Nations Security Council and War: The Evolution of Thought and Practice Since 1945 (OUP 2008) 154–171.
143. UNGA Res 76/262 (26 April 2022) UN Doc A/RES/76/262 (requiring the President of the General Assembly to convene a formal meeting within ten working days of the casting of a veto by a permanent member, to debate the situation in respect of which the veto was exercised).
144. Rebecca Barber, 'A Survey of the General Assembly's Competence in Matters of International Peace and Security: In Law and Practice' (2020) 8 Journal on the Use of Force and International Law 115.
145. Thomas Franck, ‘Who Killed Article 2(4)?’ (1970) 64 AJIL 809; Louis Henkin, ‘The Reports of the Death of Article 2(4) Are Greatly Exaggerated’ (1971) 65 AJIL 544.
146. Charter of the United Nations 1945, art 2(4).
147. Martha Finnemore and Kathryn Sikkink, ‘International Norm Dynamics and Political Change’ (1998) 52 International Organisation 900–905; Diana Panke and Ulrich Petersohn, ‘Why International Norms Disappear Sometimes’ (2012) 18 European Journal of International Relations 719, 733–735.
148. Martti Koskenniemi, From Apology to Utopia: The Structure of International Legal Argument (CUP 2005) 58–70.
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