Description:The U.S. military handed over one Iraq's key in Anbar Province Wednesday, with only four bases left to transfer before the American withdrawal by the end of year. Iraqi forces are generally seen as capable of containing a stubborn Sunni insurgency tied to al Qaeda and rival Shi'ite militias the U.S. says are backed by neighboring Iran. But insurgents still carry out almost daily bombings and attacks Almost 4,500 American troops died in Iraq since the U.S. led invasion in 2003 invasion.(1:26)