Why is the Middle East in flames and Russia on the rampage? In both Europe and the Middle East, it is common to hear the blame placed on Barack Obama. The US president, it is charged, is a weak and disengaged leader who has allowed international events to get out of control. Many Americans — both liberals and conservatives — make the same accusation. Sarah Palin, darling of the American right, has called Mr Obama “capitulator-in-chief”. Roger Cohen, a New York Times columnist, has blamed Syria’s agony on the “fecklessness and purposelessness” of the Obama administration.

Those who yearn for a more muscular US foreign policy often assume that Mr Obama will prove to be an aberration — and that the next president will “put America back in the game”. But that could well be a misreading of the underlying direction of US politics and foreign policy. The current frontrunners in the presidential election campaign — Donald Trump on the Republican side and Bernie Sanders for the Democrats — have embraced ideas that are isolationist, in all but name. If those ideas prevail, they would make Mr Obama look like a super-engaged internationalist.

Even if Mr Trump and Mr Sanders never get close to the White House, the popularity of their campaigns, and their influence on the more mainstream candidates, suggests that there is now a strong constituency in the US for a retreat from globalism: repudiating international military and economic commitments.