North Korea’s denunciation of John Bolton has forced Donald Trump to decide whether to stick with his national security adviser and his hardline tactics, or push ahead with a summit with Kim Jong-un that will provide historic spectacle but an uncertain outcome.

Underlying the plans for the Singapore summit was a fundamental ambiguity over what “complete denuclearisation of the Korean peninsula” means. For Pyongyang it is a fluid term that means a long-term process of disarmament, involving all major powers, in whose ranks North Korea would henceforward be counted a member.

The Trump administration thought it meant – or wanted it to mean – that Kim was ready to give up the arsenal he had declared complete and operational in January. For his part, the secretary of state, Mike Pompeo, who was tasked by Trump to set up the Kim summit, was ready to live with the ambiguity, at least until 12 June, when the unprecedented encounter is due to take place.