In 1963, John Kennedy warned that by the end of the 1970s as many as 25 states could hold nuclear weapons. That nightmarish world has not materialised. Indeed, in the 66 years since the US dropped the first atomic bomb, only eight further states have joined the nuclear club. Yet despite this apparent success, the risks of nuclear proliferation are not ebbing, but growing. It is time for a renewed push towards nuclear disarmament.

Two developments are inching the world towards a nuclear tipping point. The first is the Iranian nuclear programme. Were Iran to reach nuclear status, it would spark a nuclear arms race throughout the Middle East. The second is terrorists’ efforts to acquire fissile material. Proliferation to non-state actors is now as much of a threat as the spread of nuclear weapons among states. This is particularly worrying because the logic of mutually assured destruction that kept fingers off nuclear buttons during the cold war does not apply to terrorist groups.

To head off such threats, nuclear-armed states need to start shedding weapons. Until now, the drive to cut arsenals has centred on the US and Russia. That is understandable, since these two powers own 95 per cent of the world’s nuclear weaponry. But this narrow focus is also a reason that broader disarmament been conspicuous by its absence. As argued by Global Zero, an anti-nuclear group hosting a conference on disarmament in London this week, what is needed is a more aggressively multilateral approach.