Austin, Texas — The Islamic State terrorists who have emerged in Iraq and Syria are neither new nor unfamiliar. Many of them spent years in detention centers run by the United States and its coalition partners in Iraq after 2003. Abu Bakr al-Baghdadi, the leader of the Islamic State, spent nearly five years imprisoned at Camp Bucca in southern Iraq. A majority of the other top Islamic State leaders were also former prisoners, including: Abu Muslim al-Turkmani, Abu Louay, Abu Kassem, Abu Jurnas, Abu Shema and Abu Suja.

Before their detention, Mr. al-Baghdadi and others were violent radicals, intent on attacking America. Their time in prison deepened their extremism and gave them opportunities to broaden their following. At Camp Bucca, for example, the most radical figures were held alongside less threatening individuals, some of whom were not guilty of any violent crime. Coalition prisons became recruitment centers and training grounds for the terrorists the United States is now fighting.

This process began when coalition forces arrived in Iraq in 2003 and detained alleged terrorists with little preparation or oversight. Although soldiers tried to document the circumstances behind the detentions of Iraqis and foreign fighters, the process broke down under the pressure of fighting, the shortage of trained Arabic speakers, and the fog of war.

Simply being a “suspicious looking” military-aged male in the vicinity of an attack was enough to land one behind bars. There were 26,000 detainees at the height of the war, and over 100,000 individuals passed through the gates of Camps Bucca, Cropper and Taji. Quite a few were dangerous insurgents; many others were innocent.