Abstract
The prohibition on the threat or use of force, enshrined in Article 2(4) of the UN Charter, represents a cornerstone of modern international law, reflecting the post-1945 commitment to preventing the horrors of global conflict. This article examines the normative strength and practical effectiveness of this prohibition, exploring its foundations in treaty and customary law, recognised exceptions, and persistent challenges to enforcement.
Through analysis of recent cases—including Russia’s invasion of Ukraine, Israel’s military operations in Gaza, and US/UK strikes against Houthi targets in Yemen—it assesses whether the norm remains operative or has been reduced to aspirational rhetoric. While the prohibition has significantly constrained interstate aggression among major powers and achieved jus cogens status, structural limitations in the UN Security Council, expansive interpretations of self-defence, and selective compliance undermine its universality. The article concludes that the norm retains substantial resilience but requires institutional reform to enhance its operational force.
Keywords: Use of force, threat of force, self-defence, jus cogens, Security Council veto
1. Introduction
The regulation of force lies at the heart of international law. From Hugo Grotius’s early pleas for restraint in warfare to the post-World War II order, states have sought to limit recourse to armed violence. The UN Charter’s prohibition on the threat or use of force in Article 2(4) marked a revolutionary shift from the pre-1945 era, when states enjoyed near-unfettered discretion to wage war (jus ad bellum).Today, this prohibition is widely regarded as a peremptory norm (jus cogens)binding on all states.
Yet persistent violations raise fundamental questions about effectiveness. Major powers frequently invoke exceptions—particularly self-defence under Article 51—while the Security Council’s veto mechanism often prevents collective enforcement. This article critically evaluates whether Article 2(4) functions as an operative legal constraint or mere rhetorical aspiration. It proceeds by clarifying key concepts, outlining the legal framework, analysing recent practice, and offering recommendations for strengthening the norm.
2.1 Threat of Force
A threat of force comprises a state’s communicated intention to employ armed force unless specified demands are met. The International Court of Justice (ICJ) has emphasised that not every coercive statement qualifies; the threat must involve armed force and target territorial integrity or political independence.Mere possession of weapons, including nuclear arsenals, does not constitute a prohibited threat absent specific coercive intent.
2.2 Use of Force
Article 2(4) prohibits “force” in the sense of armed or military coercion, not economic or political measures. The UN General Assembly’s Definition of Aggression (Resolution 3314) provides non-exhaustive examples, including invasion, bombardment, and blockade.The ICJ distinguishes “most grave” uses constituting armed attacks (triggering self-defence) from lesser violations of Article 2(4).
2.3 International Relations
In legal terms, “international relations” in Article 2(4) denotes interactions among sovereign states governed by international law.As an academic discipline, international relations examines patterns of cooperation and conflict among states and non-state actors through diverse theoretical lenses.
3. The Legal Framework
3.1 The UN Charter
Article 2(4) provides that, ‘All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations’.
Two explicit exceptions exist:
(a) Individual or collective self-defence under Article 51, an “inherent right” exercisable only if an armed attack occurs, subject to necessity, proportionality, and reporting to the Security Council;
(b) Security Council-authorised force under Chapter VII upon determination of a threat to or breach of the peace.
Other claimed exceptions—humanitarian intervention, responsibility to protect (R2P), or pre-emptive self-defence—lack consistent state practice and opinio juris to establish customary status.
3.2 Customary International Law and Jus Cogens
The ICJ has repeatedly confirmed that Article 2(4)’s core principle reflects customary law binding even on non-UN members. Its jus cogens character precludes derogation and renders inconsistent treaties void.
4. Critical Analysis of Effectiveness
Article 2(4) has achieved remarkable normative success: territorial conquest has become rare, and direct great-power war absent since 1945. Yet enforcement remains uneven, particularly against permanent Security Council members.
4.1 Russia’s Invasion of Ukraine (2022–present)
Russia’s full-scale invasion in February 2022 manifestly violated Article 2(4). Justifications invoking self-defence, prevention of genocide, and protection of Donbas separatists were widely rejected. The UN General Assembly condemned the aggression in multiple resolutions, and the ICJ ordered provisional measures requiring immediate suspension of military operations.Russia’s veto, however, paralysed Chapter VII action, illustrating structural immunity for P5 members.
4.2 Israel’s Military Operations in Gaza (2023–present)
Israel’s response to Hamas’s 7 October 2023 attacks invoked Article 51. While the initial right of self-defence is undisputed, prolonged operations raised proportionality concerns. In South Africa v Israel, the ICJ issued repeated provisional measures under the Genocide Convention, including an order to halt military offensives in Rafah. These orders indirectly reinforce Article 2(4) scrutiny, though compliance remains contested.
4.3 US and UK Strikes against Houthi Targets (2024–present)
US and UK airstrikes on Houthi-controlled Yemen, responding to Red Sea shipping attacks, were justified as collective self-defence protecting freedom of navigation. Critics argue no armed attack attributable to Yemen occurred and that unilateral action without Security Council authorisation breached Article 2(4). The case highlights expansive interpretations of Article 51 against non-state actors.
These examples demonstrate selective application: powerful states or their allies often evade accountability through broad self-defence claims or veto protection.
5. Institutional and Normative Challenges: The Security Council’s veto power frequently blocks enforcement. The ICJ provides authoritative interpretation but lacks enforcement mechanisms. Emerging practice on cyber operations and non-state actors further strains traditional boundaries.
6. Conclusion And Recommendations
The prohibition on the threat or use of force retains substantial normative and practical force, having transformed interstate relations since 1945. It is neither pure rhetoric nor perfectly effective. Structural reform and restrained interpretation of exceptions are required to preserve its authority in an increasingly multipolar order.
Recommendation:
1. Limit veto use in mass-atrocity situations through voluntary restraint or General Assembly override mechanisms.
2. Clarify Article 51 boundaries, particularly regarding non-state actors and anticipatory self-defence, via General Assembly declaratory resolution.
3. Enhance ICJ compulsory jurisdiction through wider acceptance of Article 36(2) declarations.
4. Strengthen preventive diplomacy and compliance incentives, including targeted sanctions for violations.
5. Promote universal ratification of the Rome Statute to bolster individual accountability for aggression.
About Author
Olawuni Samuel Idowu is A sessional legal writer and researcher