When European leaders gathered at an emergency summit in Brussels, days after Mr Trump’s bombshell, the solution seemed simple enough: NATO’s 29 remaining members would regroup and marshal their defences without America. The EU had, after all, been steeling itself for this era. It had launched a European Defence Fund in 2016, which had grown from €13bn ($14.5bn) to more than €30bn. Permanent Structured Co-operation (PESCO), a scheme of joint arms production and defence integration, had followed in 2017. PESCO had already yielded a world-beating “Eurodrone”, battle-tested in the Sahel.

To be sure, this was not an EU Army. But it certainly laid the groundwork for one. At a press conference after the leaders’ emergency summit, Angela Merkel, president of the European Council, urged calm and pointed out that Europe’s collective defence spending was more than four times that of Russia. “Europe is a sleeping giant”, agreed President Emmanuel Macron of France. “We must realise our own strength.”

In practice, things were not so simple. The EU had hoped to slip effortlessly into the ready-made NATO institutions left vacant by America. That plan was, however, unexpectedly vetoed by Turkey—a member of NATO, but not the EU. Turkey’s relations with Europe had taken a sharp downward turn in 2022 after President Recep Tayyip Erdogan’s cancellation of elections and declaration of emergency rule. He relished thwarting the club that had denied him entry.