FACED WITH a collapsing transatlantic alliance, stunned European leaders this week began a diplomatic effort to salvage what is left of it, and try to bring Donald Trump back from the brink over Ukraine. On February 24th Emmanuel Macron, the French president, dashed to Washington three days before Sir Keir Starmer, Britain’s prime minister, was due to make his own visit. Mr Macron spent three hours with the American president, claiming afterwards that the talks had resulted in “substantive steps” forward.