In recent weeks, a concept once confined to academic defense seminars has entered mainstream European politics: a "European nuclear umbrella." Both German Chancellor Friedrich Merz and French President Emmanuel Macron mentioned the idea during their speeches at the Munich Security Conference on Feb. 13, while officials from countries including Poland, Estonia, Latvia, Lithuania and Belgium have also recently expressed support for it. The term "nuclear umbrella" sounds dramatic -- almost Cold War in tone -- but the idea itself is less about building new weapons than about redefining who guarantees Europe's security in an era of strategic uncertainty. The discussion is primarily driven by doubt about whether the transatlantic security model that has protected Europe for nearly eight decades will function in the same way in the decades ahead....
