In much of the world, the Predator drone symbolises US power. It is ubiquitous, stealthy and can strike at any moment. They patrol the skies of central Asia, north Africa, the Arabian peninsula – and now Iraq. Other countries have nuclear weapons and aircraft carriers. But nobody else can match the lethal ingenuity of America’s Hellfire missile. Little surprise that two US presidents – George W Bush, and now Barack Obama – have resorted to them so frequently. But their heyday is waning. America’s unipolar drone moment is ending.

Mr Obama’s chief problem is their speedy adoption around the world. Unlike nuclear weapons, there is no treaty governing the use of military drones. For roughly a decade, the Central Intelligence Agency has been able to strike targets pretty much with impunity – and blanket deniability. Of America’s partners, only the UK has been deemed fit for export. But others, including Iran, whose drones also patrol the same Iraqi skies as their US counterparts, have reverse engineered the unmanned aerial vehicle with relative ease. China is even exporting drones. Last month Saudi Arabia became its first big customer. Within five years, many countries, some of them highly unsavoury, will possess military drones, says the Rand Corporation.

All of which poses a quandary for Mr Obama and whoever succeeds him. Put simply, the US must emulate the hypocritical parent: do as I say, not as I do. Nobody wants other countries to act like the US. Many voices, including Mr Obama himself, have urged the US to put drone warfare on a transparent footing. At the moment, Mr Obama can order drone assassinations without having to admit it, or explain himself to anyone. Hundreds of militants have been killed in Pakistan, Yemen, and elsewhere. But hundreds more civilians, perhaps thousands, have also been accidentally killed.