Needless to say, what’s happening in Syria is a nightmare for those who have been forced by circumstance to bear witness to the intractable violence. The plight of the hundreds of thousands of refugees fleeing the country is unfathomable and the situation facing those who remain is even worse. For military and political strategists in Washington, Syria’s civil war represents a different kind of nightmare. The Russia-Iran nexus is just about the worst possible outcome for the US, whose status as global hegemon was already fading in the face of an ascendant China. Put simply, the partnership between Washington’s two...