The US military said Saturday it has released more than 10,000 detainees in Iraq so far this year - more than in all of 2007 - as it seeks to scale back its operation of prisons in Iraq. About 21,000 people remain in custody in Iraq, the military said in a statement. More than 8,900 people were released from detention last year. The United States wants to phase out its role of running prisons in Iraq and transfer detainees to Iraqi control. Efforts to reach that goal have been slowed partly by the lack of adequate Iraqi prison space and trained guards.