I remember an Iraqi neurosurgeon, who had just successfully defended his hospital in Baghdad against looters with a Kalashnikov in 2003, saying to me: "The Americans should remember that even Saddam Hussein had difficulty ruling this country." Iraq was never like an east European autocracy. Even under Saddam every Iraqi owned a gun. Iraqis would not fight for Saddam's regime, but they would fight for their own ethnic or sectarian community or their country. An error made by the US was to imagine that just because Shia and Sunni Arabs hated each other that Iraqi nationalism was not a potent force.