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........

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