From the end of the Second World War, the dominant current of American exceptionalism in the rhetoric and outlook of US presidents has been the belief that the United States has a special mission to redeem the world by extending liberty and democracy to all peoples. However, President Donald Trump is an exception. He believes that in the post-Cold War era successive administrations in Washington have pursued reckless visions of regional or global hegemony — especially in the Middle East — leaving the home front to languish and the nation open to ridicule. For Trump, the government must first protect its citizens and promote their prosperity. Despite eschewing this stream of American altruism, Trump wants to “make America great again” by rebuilding its economy and projecting military strength. In his first 18 months in office few policy decisions have exhibited either isolationism or a willingness to countenance American retreat from the world. Still, Trump is no internationalist, and has never expressed support for the institutions of global governance that emerged after 1945. Moreover, his long-standing impatience with alliances and hostility towards free trade and other multilateral approaches to international affairs have now found concrete, if inconsistent, expression in his presidency. Trump’s America First impulses are hardening as he gains greater confidence on the world stage and reshapes his national security team. His stoking of the politics of grievance and resentment will, however, continue to corrode domestic support for a more ambitious US foreign policy, and in future allies will have to think about the nature of American power differently.