“Sit long enough by the river and the corpse of your enemy will float by,” says an old Middle Eastern proverb. For Iranian leaders, the truth of this saying has been proved this spring as the Arab Awakening unexpectedly overthrew or weakened their enemies across the region. As recently as January, the White House was satisfied that it was gradually tightening the noose around the neck of Iran as it imposed ever more severe sanctions on its old foe. But within three months, without Iran actually doing anything, American policy was in fragments. One stalwart of the anti-Iranian alliance, President Hosni Mubarak of Egypt, was in hospital under arrest – and another, King Abdullah of Saudi Arabia, had plenty to worry him close to home in Bahrain and Yemen; urging an aggressive policy towards Iran, the king had once advised Washington “to cut off the head of the snake”, but as revolution sweeps the Arab world, the United States is losing whatever small appetite it had for a confrontation with Iran.