Donald Trump has a point when he complains about foreigners who “rip us off on trade”. There are countries that do just that. But while the US president chases phantoms of tariffs and trade deals, the real sharp practice is currency manipulation.

In the 1990s and 2000s, numerous countries — but most notably China — held down their currencies in order to run a large trade surplus. This came at the expense of US (and UK) deficits. The actions of currency manipulators sped the decline of western manufacturers and contributed to the 2008 financial crisis.

Some countries still manipulate their currency today. Stopping them would be an excellent way to tackle global trade imbalances. That Mr Trump has launched a round of pointless tariff wars is doubly unfortunate, because there is a golden opportunity to forge a new alliance against currency manipulation, and end the practice for good.