For years, U.S. presidents have complained that European governments spend far too little on their militaries, leaving the United States to pick up a disproportionate share of the tab for the transatlantic alliance. But in the past few years, Europe’s defense spending has exploded. At the NATO summit last week, U.S. allies committed to spending five percent of GDP on defense. That’s far more than the two percent target U.S. policymakers long called for. It’s even more than the United States itself spends on defense—the result of both escalating pressure from U.S. President Donald Trump and escalating threats from Russian President Vladimir Putin. But Celeste Wallander, until recently the top defense official overseeing U.S. policy toward Europe and Russia, warns in a new Foreign Affairs essay that this transformation will have more complicated consequences than most Americans expect. A more capable Europe will also mean a more independent Europe, more willing to defy U.S. priorities and make demands for cooperation. Wallander has been a key player in the transatlantic alliance as a top official on the National Security Council and in the Pentagon, including as assistant secretary of defense for international security affairs during the Biden administration. She is now executive director of Penn Washington and an adjunct senior fellow at the Center for a New American Security. The United States, in her view, will have to take a very different approach to the transatlantic alliance—at a time when it’s as vital as ever, in Ukraine and beyond. You can find sources, transcripts, and more episodes of The Foreign Affairs Interview at https://www.foreignaffairs.com/podcasts/foreign-affairs-interview.