The door opened for ISIS in Iraq when the US, in 2011 pulled the last of its combat troops from the country, leaving in its stead a coalition government lead by Iraqi Prime Minister Nouri al-Maliki. Al-Maliki, who is also a Shiite Muslim, made matters worse as he purged the coalition government of any Sunni and Kurdish politicians immediately upon the US's exit.
Staff Reporter
By removing the remaining Sunni and Kurdish politicians left in his government, al-Maliki would once again incite the sectarian violence that led to the US's protracted stay in the country after the defeat of Sunni President Saddam Hussein. Along with the absence of the US in Iraq, ISIS benefited from the trouble that Syrian President, Bashar al-Assad faced as his country descended into civil war calling for his resignation. Because the al-Assad regime focused on maintaining a firm grip on some of its key cities, like Aleppo and Damascus, the focus on securing its borders and other cities of strategic value were put on the back burner. ISIS seized upon this opportunity, and moved into Syria seemingly overnight.