T he US "surge" in Iraq has been so manifestly successful that no serious person can deny that gains have been made. Even Hillary Clinton and Barack Obama have (grudgingly) conceded progress. Yet both Mrs Clinton and Mr Obama are quick to add that progress has been purely on the military side and that those gains are ephemeral. This fits with their broader narrative - that the war has been a disaster on every front.

During a recent Democratic debate, for example, Mr Obama declared: "We are seeing al-Qaeda stronger now than at any time since 2001." Mrs Clinton says President George W. Bush's policies in Iraq have "emboldened our enemies". We should leave Iraq, she says, so we can better focus on the threat of al-Qaeda.