Israel/Iran: What are the ethical and legal limits of self-defence?

On 12 June, Israel initiated a devastating series of strikes on Iran — the goal of which was evidently to diminish the nation’s increasingly problematic nuclear program and to “decapitate” the nation’s top military leaders and nuclear scientists. There is no doubt these attacks were meticulously planned and represent the culmination of a long-term strategy: to neutralise the threat posed by Iran and its proxies in Lebanon, Yemen and Gaza.

The timing and urgency of the strikes, however, have puzzled many. After all, they came little more than a week prior to the scheduled latest round of talks between the United States and Iran on the future of the latter’s nuclear program. The precipitating event seems to have been the release of a recent report by the International Atomic Energy Agency (IAEA), which found that “Iran can convert its current stock of 60 percent enriched uranium into 233 kg of WGU in three weeks … enough for 9 nuclear weapons”, and that “Iran is undertaking the near-final step of breaking out, now converting its 20 percent stock of enriched uranium into 60 percent enriched uranium at a greatly expanded rate”.

Such findings would certainly have been central to US-Iran talks. But they were taken by Prime Minister Benjamin Netanyahu as posing a clear and imminent threat to the State of Israel, and therefore as justifying a preventive attack.

Iran then unleashed a series of missile strikes of its own, citing justification on the grounds of “self-defence”. We have, in other words, two nations claiming to be acting in self-defence. But this isn’t peculiar to this specific conflict between historically hostile nations. Prior to the 2003 invasion of Iraq, the United States asserted a right to “pre-emptive self-defence”. Vladimir Putin justified Russia’s invasion of Ukraine in 2022 as an act of “self-defence” against a future attack.

“Self-defence” thus seems to have become a legally and politically promiscuous term, and can thus be used to justify actions in which no imminent threat is present and for which alternatives are available. What, then, are the legal and philosophical limits to claims that one is acting in “self-defence”, particularly when that entails pre-emptive violence?