While it is possible to provoke Iran, North Korea, or street protesters to provide an excuse, the novel factor here is that Mr. Trump is in a position to raise fear at a nuclear level. This leads back to the illegal appointments of Secretaries of Defense and Homeland Security. He also fired the head of the National Nuclear Security Administration, and eliminated that agency’s independent status. Even if all these new appointees are honest and loyal, they have only just arrived in their posts, and their tenure in them is uncommonly fragile and tentative. Their first instinct will be to believe and support, creating a shade of plausibility that could lead others to hesitate in the required manner.