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Some insights from the US strikes in Iran: Aggression and the limits of self-defence | The Leaflet

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Some insights from the US strikes in Iran: Aggression and the limits of self-defence

Since the US military aircraft attacks on three Iranian nuclear facilities last week, international law experts have been split on whether there was a violation of international law. A close examination of the attack makes clear that they constituted ‘aggression’, an aggravated form of ‘use of force’, and hence the U.S.’s position of portraying the attacks as self-defence is largely untenable.

Atul Alexander

Published on: 28 June 2025, 01:54 pm

Some insights from the US strikes in Iran: Aggression and the limits of self-defence

THE UNITED STATES’ (U.S.) ATTACKS on the Iranian nuclear facilities last week sent shock waves across the world. It reminded us of Israel’s 1981 strikes on the Osirak nuclear reactor in Iraq, which involved the Israeli Air Force partially destroying it.

The actions of the U.S have been met with mixed responses. The NATO Secretary-General Mark Rutte dubbed it as not violative of international law. Meanwhile, Russia termed the U.S strikes as unprovoked and unjustified. The U.S.’s position was echoed by U.S. Defence Secretary Pete Hegseth who stated that “[t]he president authorised a precision operation to neutralise the threats to our national interest posed by the Iranian nuclear program and the collective self-defence of our troops and our ally Israel.”

International law scholars like Donald Rothwell reckon that the sole legal justification available to the U.S is the doctrine of self-defence. The doctrine could be either activated through the United Nations Security Council (‘UNSC’) resolution or if there is a prior armed attack which justifies the exercise of self-defence against another State.

Despite the attack by Hezbollah and Houthis targeting the U.S. assets, there appears to be no nexus for the attacks on the nuclear installments. Arguments are also made justifying the attack on the grounds of preemptive and anticipatory self-defence. In 2003, the Bush administration forwarded the latter doctrine to support its intervention in Iraq on the grounds of an imminent threat. Beyond this, the doctrine finds limited support.

In this article, I contend that the U.S. attacks on the nuclear installations constitute aggression (an aggravated form of use of force), which is an integral part of jus cogens norm. Thus the U.S. attacks went beyond the conventional reasoning of use of force, and hence, the U.S. was unauthorised from taking the defence of self-defence.

First, the UNGA Resolution 3314 lays down a list of acts that constitute aggression. Specifically Article 3(d) of the resolution reads, “An attack by the armed forces of a State on the land, sea or air forces, or marine and air fleets of another State”. The U.S. B-2 bomber dropped bombs over the nuclear sites in Fordow, Natanz and Isfahan.

Trump claims the strikes “completely…obliterated” Iran’s nuclear enrichment facilities. According to the Secretary of Defence Pete Hegseth, the attack has ‘obliterated Iran's nuclear ambition.’ Therefore, these air attacks unambiguously constitute aggression. The rationale behind these attacks and coercive diplomacy is to thwart the Uranium enrichment and curb the regional hegemony of Iran.

However, this legally does not entitle the U.S. to commit aggression. As the UNGA resolution highlights, “[N]o consideration of whatever nature, whether political, economic, military or otherwise, may serve as a justification for aggression.” Therefore, self-defence cannot be a ground to justify aggression because it is immune to exceptions.

Second, on several occasions, the International Court of Justice (‘ICJ’) had the opportunity to interpret self-defence for acts of aggression. In the Nicaragua case (1986), the United States tried to deploy collective self-defence for Nicaragua’s alleged acts of aggression against El Salvador, Honduras and Costa Rica. However, the U.S. failed to fulfil the requirement of self-defence, as the ICJ observed, “The declaration and the request of El Salvador made publicly for the first time in August 1984, do not support the contention that in 1981 there was an armed attack capable of serving as a legal foundation for United States activities which began in the second half of that year.”

Prohibition of aggression is a jus cogens norm; this implies the norm cannot be exempted or derogated. Hence, the U.S cannot activate self-defence in any format, as this would abrogate the norm in question and exacerbate the West Asian crisis.

In DRC v. Uganda (2005), Uganda tried to justify DRC’s allegation of aggression, where Uganda tried to justify its position through self-defence. Unfortunately the ICJ did not respond to the contentions of the Parties as to whether and under what conditions contemporary international law provides for a right of self-defence against large-scale attacks by irregular forces, as the attacks were non-attributable to DRC. This opinion needs to be read with caution as this was in the backdrop of attacks carried out by non-state actors against another State, unlike the direct attacks by the U.S. in Iran. Also, in his separate opinion, Judge Bruno Simma regarded it as a classic case of aggression.

Third, the jus cogens nature of aggression means it cannot be derogated or exempted. Article 26 of the ILC Draft Articles on State Responsibility states, “Nothing in this chapter precludes the wrongfulness of any act of a State which is not in conformity with an obligation arising under a peremptory norm of general international law.” One of the exceptions identified by the Draft is self-defence, which cannot be justified as precluding wrongfulness because the commission of aggression breaches a jus cogens norm. Notably, though, the ILC Draft does not address the question of commission of acts of aggression, as this is within the ambit of the primary rule. The U.S. has violated the rule in contention as evident from the attacks.

Conclusion

Prohibition of aggression is a jus cogens norm; this implies the norm cannot be exempted or derogated. Hence, the U.S cannot activate self-defence in any format, as this would abrogate the norm in question and exacerbate the West Asian crisis. The violations of the U.S. would entail consequences under the secondary rules of State responsibility for serious breach.

Therefore, States are obligated to cooperate through lawful means to end the breach. Thus, there could still be room for diplomacy considering President Trump’s propensity to restart negotiations. Also, the third States are obligated not to aid and assist in an unlawful situation created by the breach.