The charge that the joint Israel–US campaign against Iran is illegal rests on an interpretation of international law that cannot survive contact with reality. If the law truly forbade a country from pre-empting a regime that has spent decades arming proxies, pursuing nuclear arms and calling for its destruction, then such a doctrine would be unfit for purpose. International law was designed to reduce instability, not to condemn those marked for annihilation to passively await their fate.
Nor is the legal position as straightforward as critics suggest. This is not a new war of choice but the continuation of a conflict that began in 1979, when the Islamic Republic enshrined Israel’s destruction as state policy. It was operationalised over decades, largely through terror proxies, allowing Tehran to prosecute its campaign while avoiding formal accountability. October 7 was the most brutal manifestation of that design. Hamas carried out the massacre but Iran built the ecosystem that made it possible.
But at least since April 2024, when Iran fired the first of hundreds of missiles at Israel, the two countries have been in direct confrontation. On any reasonable reading, this is an ongoing armed conflict and Israel’s current strikes are therefore lawful. The US has the right to stand by a major non-Nato ally facing a regime that has also targeted American personnel and interests for decades.
A related debate turns on whether there was an imminent threat. But the right of self-defence does not require a state to wait politely while a hostile power assembles its arsenal. And the threat is not limited to nuclear weapons alone. Despite the 12-day war last year – which severely damaged Iran’s military infrastructure – Tehran resumed not only its nuclear programme but accelerated its missile production capacity on a scale that would soon pose an existential threat to Israel in its own right. And by accelerating work at Pickaxe Mountain – constructing hardened facilities to shield key elements of its nuclear programme from even the most powerful American munitions – Iran was further narrowing the window for pre-emption.
It is therefore striking that Attorney General Lord Hermer, in an area where the law is at the very least contested rather than settled, reportedly favoured an interpretation that led the British government to withhold full backing from its American and Israeli allies – a position that sits uneasily alongside the support offered by other left-leaning governments in Canada and Austria.
When the law is ambiguous, governments make strategic choices. In this case, Britain appears to have chosen an interpretation that overlooks not only the national security interests of its allies, but also its own. After all, Iran has long called also for “Death to the UK” and has been linked to multiple terror plots on UK soil.
For too long, many European leaders have behaved as if military conflict were a relic of the past and all inter-state disagreements could be adjudicated away in international courts. That presumes a world in which all actors voluntarily accept the so-called rules-based order. But regimes such as those in Tehran or in Moscow do not. Even after Russia’s invasion of Ukraine shattered illusions about the permanence of peace on the European continent – and reimposed the necessity of hard-power realism – reflexive calls for de-escalation persist, nowhere more so than when Israel is involved.
Yet the tone has begun to shift. German Chancellor Friedrich Merz has warned against “lecturing allies” and acknowledged “shared strategic goals”. Nato Secretary General Mark Rutte has been explicit that “it’s really important what the United States is doing here together with Israel,” adding that degrading Iran’s nuclear and ballistic missile capabilities serves wider security interests. Such realism is long overdue.
As we have just marked Purim – recalling an ancient plot that also emanated from Iran – the historical echo is difficult to ignore. Then, as now, survival depended not on declarations, but on action.
And if the present campaign decisively weakens – or removes – the regime that has destabilised the Middle East for decades, the consequences will extend far beyond Israel’s security. The region would no longer be held hostage to Tehran’s strategy of proxy warfare and terror.
The Iranian people, who have repeatedly challenged clerical rule at great cost, could finally reclaim their future. The public celebrations of Iranians and Jews at the news of Khamenei’s death – and expressions of Iranian gratitude toward Israel for confronting a regime that has murdered tens of thousands of its own citizens – offer a glimpse of what might follow. An ancient relationship between Iranians and Jews, buried under decades of ideological hostility, could re-emerge.
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