“The dollar always talks in the end,” Donald Trump wrote in his 1987 bestseller The Art of the Deal. Javier Milei’s surprise triumph in Argentina’s midterm elections – after Trump bailed him out with 40bn of them – suggests there may be some truth to that assertion. The US president had vowed to jettison his South American ally if, as widely predicted, the radical libertarian fared badly in Sunday’s make-or-break legislative vote. “If he doesn’t win, we’re gone,” Trump declared when Argentina’s shaggy-haired president visited him in Washington earlier this month to plead for economic help. Milei’s political woes have...