A second argument is that, while Iran may not deploy nuclear weapons against Israeli directly, it might encourage proxies or terrorist groups to do so. But as Mr Waltz writes, two things work against this: it would be easy to discover Iranian responsibility, and countries that develop nuclear weapons generally retain tight control over their arsenals. “After all, building a bomb is costly and dangerous. It would make little sense to transfer the product of that investment to parties that cannot be trusted or managed,” he believes.

Iran’s intention to closely monitor its weapons was plain during the Lebanon war of 2006, when the Iranians apparently gave final approval for use of, or even operated, Hizbollah’s most advanced systems. But that begs another question, namely whether an entirely trusted Hizbollah might receive nuclear weapons from Iran.

Such an alternative cannot be discounted, but it is improbable. First, Israel would not hesitate to engage in a ferocious pre-emptive strike against Lebanon, perhaps even initiating a ground war to prevent such an outcome. And Lebanese society, with many Shia among them, recognising the potentially disastrous consequences of a nuclear-armed Hizbollah, would angrily challenge the party, undermining the national unity required to give a nuclear deterrent its value.