Some illegal uses of force have been judged morally defensible, as in Kosovo in 1999. But the US–Israel war on Iran fails that test – lacking lawful authority, credible motives and a plausible path to a better outcome.

In international relations, manifestly illegal government action can sometimes be morally defensible. While historical examples of legitimacy trumping legality are few and far between, they do exist. The question of whether the joint US-Israeli war on Iran is one such case demands more attention than it has received so far.

It should be beyond dispute that the initiation of this war by US President Donald Trump and Israeli Prime Minister Benjamin Netanyahu flagrantly violated international law, even if many of their allies have shown a willingness to fudge this issue. Iran did not pose a threat to either country – from nuclear weapons, conventional missiles, or state-sponsored terrorism – of an imminence or on a scale that could possibly justify, in the absence of the UN Security Council’s approval, preemptive military action as a form of self-defence. The United States and Israel acted when they did not because of Iran’s strength, but its relative weakness.

The attack is just the latest in a series of actions by the world’s most powerful countries – including Russia’s invasion of Ukraine, China’s militarisation of the South China Sea, and America’s seizure of Venezuelan President Nicolás Maduro – that disdain international law.

The collapse of whatever is left of a rules-based order is bad news for the........

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