Among the oddities of Donald Trump’s negotiating style is his willingness to reveal his hand.

“All we have to do,” the US president said of the EU last week, “is tax their cars and they’d give us anything we wanted because they send millions of Mercedes over”. The wisdom of this tactic, which Niccolò Machiavelli did not find room for in The Prince, is questionable.

So too is his choice of opponent. Despite his singular focus on China, Mr Trump has actually fallen out with Europe over a wider range of items. He resents what he sees as the military burden-shirking of Germany and other Nato members. He has threatened to “release” Islamic State members into France. Denmark rebuffed his bid to replay the 1803 Louisiana Purchase of the US midwest with Greenland.