UMM QASR, Iraq -- Hurling rocks, bottles filled with sand and wooden stakes, detainees at the only permanent U.S. prisoner-of-war camp in Iraq riot almost daily, military officials said Sunday. Anger over slow food lines or disputes among ethnic groups can spark uprisings--especially with ringleaders quick to incite riots inside the prison camp that houses about 6,000 Iraqis under long white open tents, they said. "Pretty much every day there's a riot. It can get real ugly in there for the MPs [military police]," said Maj. Joel Droba of the 13th Psychological Operations battalion, which broadcasts orders for calm over...