This isn’t to say that direct meetings are not a good idea. Sanctions are biting deeply in North Korea, and China is clearly fed up with its bizarre ally. But a summit should be a reward for months, even years, of careful work and actual progress. Meetings at lower levels should progress to more senior principals, and then to the heads of state.

Instead, we have yet another decision, much like the recent and incoherent announcement of tariffs, that looks like sheer impulse from a commander-in-chief who seems frustrated that his advisers keep telling him that nuclear diplomacy is more complicated than running a hotel or a golf course.

Worse yet, the short fuse for a meeting in May — and why the hurry?— means that this will be a summit without an agenda and with no time to devise one, which always increases the chances of a diplomatic train wreck. There is no evidence that this move was given any kind of serious analysis by military or diplomatic advisers. The Pentagon seems to be in the dark, and Secretary of State Rex Tillerson made clear just hours before the announcement that no such meeting was even on the horizon.