In Roman times, judges would ask: cui bono — who benefits? When asked of Donald Trump’s erratic foreign policy, the answer is troubling. The biggest winner of Mr Trump’s “America First” doctrine is Russia, not the US. Mr Trump’s own yardstick yields poor results. It is hard to measure whether he has made America great again. But he is missing his specific goals.

America’s trade deficit with China last year was a fifth larger than in Barack Obama’s last year in office. Its global trade gap last year was $148bn higher than in 2016. Germany’s defence spending, meanwhile, is set to fall. At 69 per cent, America’s share of Nato spending is unchanged.

Such results offer little to brag about. The same applies to the diplomatic coups Mr Trump is trying to pull off. The biggest are a nuclear deal with Kim Jong Un’s North Korea, a new Iran agreement to replace the nuclear one struck by Mr Obama and the “deal of the century” between Israel and the Palestinians. Each is in trouble.