Although none of them predicted a return to the anarchy and sectarian carnage of 2006-2007, when scores of bodies might show up in the street on any day, officials suggested that the groups were preparing for the onset of a U.S. military withdrawal.

Their warnings make for an irony at the beginning of the end of the American presence here. As the United States dismantles Bucca, viewed by many as an appalling miscarriage of justice where prisoners were not charged or permitted to see evidence against them, freed detainees may end up swelling the ranks of a subdued insurgency.