Self-defence?

As the dust settles from the 12-day conflict that began with Israel’s “Operation Rising Lion” on 12 June 2025, and escalated with U.S. strikes on June 22, an urgent question arises: Were these pre-emptive attacks on Iranian nuclear facilities lawful under international law? Both countries claim the strikes were acts of self-defence against an existential nuclear threat. Yet, the core legal issue is whether such anticipatory use of force aligns with Article 51 of the UN Charter, or whether it signals a dangerous erosion of international norms regulating jus ad bellum. Historically, Israel had in – vok ed similar reasoning in its 1981 strike on Iraq’s Osirak reactor and the 2007 bombing of Syria’s Al Kibar facility. In each case, Israel claimed self-defence against emerging nuclear threats. However, neither reactor was operational, and both atta – cks drew criticism for lacking legal justification under Article 51.

The strikes on Iran have provoked similar condemnation. Iran denies any active weapons programme and appealed to the UN Security Council. Legal experts remain divided ~ some suggest anticipatory self-defence may be valid if an imminent threat is evident; others argue that the lack of verified intelligence renders these strikes as preventive self-defence, a doctrine widely rejected by international law. The UN Charter’s Article 2(4) prohibits the use of force, with exceptions under Chapter VII (Security Council authorization) and Article 51 (self-defence against an armed attack). Customary international law, as affirmed by the ICJ in Nicaragua v. United States (1986), also reinforces this framework. Self Defence under Article 51 is tightly constrained by the principles of necessity and proportionality. The ICJ has consistently ruled that only an actual armed attack triggers the right of self-defence.

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The 2003 Oil Platforms case reiterated that anticipatory strikes based on threats or speculative dangers fall outside the legal bounds. Nevertheless, some states advocate broader interpretations. Scholars like Yoram Dinstein argue that states need not “wait for bombs to fall.” The U.S. historically endorses a flexible reading of “imminence,” especially in contexts involving WMDs and terrorism, as articulated in the 2002 National Security Strategy. However, the Caroline doctrine remains the prevailing legal standard for anticipatory self-defence: the necessity must be “instant, overwhelming, leaving no choice of means, and no moment for deliberation.”

The more radical extension, preventive self-defence, has no legal basis in contemporary international law. The UN High-Level Panel (2004), the ICJ, and most states categorically reject it, viewing it as undermining the Charter’s restrictio – ns. Israel argued its June 2025 strikes were necessary to prevent Iran from acquiring nuclear weapons, claiming credible intelligence pointed to an imminent nuclear threat. Invoking Article 51, it maintained that the action met the legal test of necessity, proportionality, and imminence. However, Israel’s historical warnings about Iran’s nuclear ambitions ~ especially under Prime Minister Netanyahu ~ have often lacked verification.

The IAEA reported in 2023 that Iran had enriched uranium up to 60 percent but had not moved toward weaponisation or developed delivery systems. There is no verified evidence of an imminent nuclear attack. The U.S. supported Israel, citing collective self-defence and invoking Article 51 in a letter to the Security Council. President Donald Trump characterised the action as a “limited and necessary” strike to prevent Iran’s nuclear breakout. The U.S. argued for a relaxed standard of imminence due to the unique threat of nuclear weapons. Yet, the ICJ’s Nicaragua ruling stipulates that collective self-defence is lawful only if the assisted state (Israel) suffers an armed attack. Since Israel was not attacked, U.S. involvement lacks an independent legal basis.

Both countries argued that the threat from Iran’s nuclear programme warranted immediate action. However, for anticipatory self-defence to be lawful, two core conditions must be met: imminence and proportionality, based on verifiable intelligence. In this case, neither Israel nor the U.S. provided public or independently verified evidence of an imminent Iranian attack. Iran has made no recent threats, and the IAEA continues to monitor its activities without confirming any shift toward weaponisation. Intelligence cited by Israel was neither disclosed to the Security Council nor shared with international agencies. Moreover, necessity and proportionality require force to be a last resort. Israel by passed diplomatic measures, failed to involve the Security Council under Chapter VII, and ignored regional mechanisms for conflict resolution.

These omissions undermine the argument that military action was necessary. The strikes appear more aligned with preventive self defense, aimed at neutralising a perceived future threat, a doctrine overwhelmingly rejected in legal scholarship and state practice. Countries like Germany, France, Japan, and Switzerland have reiterated that self-defence is lawful only in response to an actual or imminent attack, not speculative threats. The claim that nuclear risks demand a looser standard of imminence is also unconvincing. While nuclear capabilities do raise serious concerns, capability cannot be equated with intent.

Accepting this logic would allow virtually any state to attack others based on hypothetical dangers ~ a slippery slope that threatens the entire jus ad bellum regime. The legal arguments ad – vanced by Israel and the U.S. starkly contrast with their own condemnation of Russia’s 2022 invasion of Ukraine, which Moscow justified as anticipatory self-defence. Both countries dismissed Russia’s claims as violations of Article 2(4). If anticipatory self-defence based on speculative threats was invalid in 2022, it cannot be selectively validated in 2025. Applying different legal standards in similar contexts opens both nations to accusations of hypocrisy and instrumentalism.

It also weakens the credibility of the self-defence framework and encourages other states to misuse similar justifications for aggressive wars. The Israeli and U.S. strikes on Iran’s nuclear facilities in June 2025 were not authorised by the Security Council, nor were they responses to an actual or imminent armed attack. No publicly available evidence supports the claim of an imminent Iranian threat. These actions fall outside the lawful scope of Article 51, and instead fit the discredited doctrine of preventive self defense. Such use of force, lacking both imminence and necessity, risks being classified as aggression under international law.

Even if Iran’s nuclear programme raises legitimate concerns, those concerns do not meet the legal threshold for military action. Upholding the Charter framework means rejecting pre-emptive war as a legal norm – regardless of how compelling the strategic rationale may seem. Permitting strikes based on speculative threats would erode the foundational principles of the UN Charter, invite global instability, and dangerously blur the lines between law and power. The world has already witnessed the long-term consequences of preventive war in Iraq (2003) and Ukraine (2022). Repeating that logic now threatens to collapse the post-1945 legal order designed to limit war, not enable it.

(The writer teaches international law at Aligarh Muslim University and heads its Strategic and Security Studies)