“He’s gaining a lot of confidence, Mike, isn’t he?” That was Donald Trump in the White House Rose Garden on Wednesday afternoon, talking rather indulgently about his 40-year-old vice-president JD Vance to House Speaker Mike Johnson — just before announcing heavy tariffs on most of America’s major trading partners.

Trump might have been wrong to celebrate the unleashing of a global trade war as “liberation day”, but he was not wrong on Vance. After all, a man?who feels qualified to talk to the heroic president of a war-ravaged country as if he were a small child — demanding that Volodymyr Zelenskyy say thank you to the US president, who had recently described him as a “dictator without elections” — is nothing if not confident.

The same confidence, to which I might add arrogance and ignorance, was on display during Vance’s recent unsolicited visit to Greenland. The vice-president, with his characteristic mixture of earnestness and cloddishness, berated Denmark — a country he had previously accused of “not being a good ally” — for failing to protect Greenland from the threats of Russia and China. “Our message to Denmark is very simple: you have not done a good job by the people of Greenland,” Vance told an audience at an American military base. “You have underinvested in the people of Greenland and you have underinvested in the security architecture of this incredible, beautiful land mass, filled with incredible people.”