Donald Trump has wrecked the best plans of nearly a score of "serious" Republican presidential candidates. Yet what may be most extraordinary about his campaign is that on foreign policy, at least, he may be the most sensible Republican in the race. It is the "mainstream" and "acceptable" Republicans who are the most extreme, dangerous and unrealistic.

First, the Republicans scream that the world has never been so dangerous. Yet when in history has a country been as secure as America from existential and even substantial threats?

Hyperbole is Trump's stock in trade, but he has used it only sparingly on foreign policy. Referring to North Korea, for instance, he claimed: "This world is just blowing up around us." But he used that as a justification for talking to North Korea, not going to war.