The Brexit, along with Donald Trump’s criticisms of NATO, have raised questions about what a dissolution of these two multinational institutions might mean for the security and interests of the U.S. Despite justified criticisms of European NATO members’ failure to meet their financial obligations, NATO is unlikely to unravel. The British departure from the EU is more portentous. Longstanding problems with the EU reflect structural deficiencies that may not be amenable to further policy adjustments. A breakdown of the EU, however, could free up European nations to craft defense pacts and increase defense spending that would benefit America’s security.