The US commitment to Europe is noble, a human-lifetime old and vastly successful. That does not stop it being slightly weird. Thirty years after the fall of the Soviets, for instance, the US continues to garrison a Germany that is not just rich but, on recent form, more internally stable than its nominal protector.

One explanation is that Russia is still a force that needs discouraging. Another is that Europe is a lily-pad for US actions in the Middle East and elsewhere. The first reason does not say why Americans, an ocean away, should form a large part of the discouragement. The trouble with the second is its open-endedness.

If the continent is strategically placed now, when will that ever stop being true? The implication is an eternal US role there. It does not take an America First-er to wonder at the warping effects on both the US and its host nations. It does not take a euro-federalist to sense that it stunts the continent’s growth into self-reliance.