Mark Rutte, the Nato secretary general, has a reputation for genial flexibility and an ability to evade trouble. During his record-breaking 14 years as prime minister of the Netherlands, he earned the nickname ‘Teflon Mark’.

He came to the job at a highly challenging time, a month before Donald Trump was elected to a second term as president. Rutte, more than anyone in Europe, knew the extent of Trump’s antipathy towards the alliance. At a tense meeting at Nato headquarters in Brussels in 2018, President Trump launched into a tirade in which he threatened that the United States would go its own way unless its allies increased military spending. Rutte, witnesses later said, had deftly changed the tone, arguing that spending had indeed risen, and that Trump deserved the credit. The president was mollified.

In a second Trump presidency, the threat to Nato’s stability and solidarity is even more acute. Both secretary of defence Pete