 Malise Ruthven writes that the post invasion de-Ba'athification by the US occupiers deprived Iraq of "the officer class and administrative cadres that had ruled under Saddam Hussein, leaving the field to sectarian-based militias".Many of officers joined the anti-Shia takfiri ISIL group.The US-led invasion also “tilted the regional balance of power decisively" in favor of Shia Iran, alarming Sunni and leading to talk of a “Shia Crescent”.