McCain’s confusion has been widely characterised as demonstrating his inability to distinguish Sunni al Qaeda from Shiite Mahdi Army. But more fundamentally, McCain’s gaffes were a reflection of how thoroughly he had internalised a favourite theme of the Bush administration and neoconservatives — that Iran has tolerated and even covertly assisted al Qaeda agents operating inside Iran.

Those administration charges have continued despite the repeated release of information by Iran and other countries about its arrest, detention and repatriation of al Qaeda suspects.

Nevertheless, Bush administration officials carried out a determined campaign of press leaks in 2003 and 2004 suggesting covert Iranian support for al Qaeda terrorism.