On one thing everyone lining up for next year’s US presidential race can agree. Barack Obama has led from behind on the global stage. The president has been shy about deploying US might, accommodating of adversaries and reticent about standing up for allies. His successor in the White House, we are to believe, will restore America’s global prestige by standing up to China, facing down Russia and sorting out the Middle East.

An old friend in Washington, a foreign policy veteran of the Reagan administration, calls this a “bumper sticker” view of the world. He is right.

The chatter in an already crowded Republican field is that 2016 will be a “foreign policy election”. Republicans fear that a buoyant economy will narrow the range of domestic targets. National security offers obvious opportunities. The march across Syria and Iraq of the self-styled Islamic State of Iraq and the Levant (Isis) has revived fears of attacks on the US. Mr Obama’s proposed deal with Iran falls short of the scrapping of Tehran’s nuclear programme. Russia’s Vladimir Putin is menacing America’s European allies.