Sign up for the Slatest to get the most insightful analysis, criticism, and advice out there, delivered to your inbox daily. Over just this past week, Donald Trump has done more to rip apart the U.S.–European alliance than any foe has managed to do in the partnership’s 75 years. The barn burner was Vice President J.D. Vance’s speech Friday at the Munich Security Conference, in which he proclaimed that the biggest danger to Europe is not Russia or China but rather the “threat from within.” He was talking not about the rise of far-right authoritarian parties but about precisely the...