Trump’s loose talk about buying Greenland from Denmark or even conquering it grabbed the headlines and panicked European politicians. The Danes and their European allies sent a token force of human tripwires to Greenland. Trump retaliated with tariffs on eight European states, including Britain, France, and Germany, starting at 10% on Feb. 1 and rising to 25% on June 1. Privately, European officials called Trump “crazy” and “mad” and called his unprovoked “attack” a “step too far.” French President Emmanuel Macron called the tariff threat “unacceptable.” British Prime Minister Keir Starmer called it “completely wrong.” Trump was unmoved. “We have...