America and Europe hail Ukraine’s resolute fighting spirit, which raises a nagging question: why are they not sending more weapons, more quickly? Officials’ answers vary: the West is moving with unprecedented speed; it is giving priority to weapons that are most urgently needed; it has to train Ukrainians to use and maintain their new kit; and they have to show they can use it effectively in battle. Javelin anti-tank missiles, forbidden by America when Russia took the first chunks of Ukraine in 2014, came in a trickle from 2017 and then a flood when Russia invaded again in February. Stinger anti-aircraft weapons, similarly refused, arrived in March. What would push the West and Russia to nuclear war?

