Donald Trump’s possible return as US president has again raised the spectre of the United States’ abandoning its central role in the European security order. Given the profound polarisation and insularity that has arisen in US politics, transatlantic relations might not readily return to the traditional comfort zone even if Joe Biden is re-elected. In Europe, vigorous public discussion has arisen on ramping up defence-industrial capabilities to help Ukraine and to reduce European dependence on the US; on the future of US extended nuclear deterrence; and on France’s readiness to give a specifically European dimension to nuclear deterrence. Europe’s ability to prepare constructively for a diminished American security role will hinge on the European trend of rising populist-fuelled authoritarianism, and on the customary difficulty France and Germany have in crafting a joint approach to strategic planning.