BAGHDAD, Feb 8 (Reuters) - The new U.S. military commander for Iraq, General David Petraeus, has arrived in Baghdad as an offensive against militants in the capital gets under way, a U.S. military official said on Thursday. The operation is seen as a final attempt to halt all-out civil war between Iraq's politically dominant Shi'ites and former ruling minority Sunni Arabs. Petraeus will take over command from General George Casey at a ceremony on Saturday. The U.S. military official did not give any more details. U.S. President George W. Bush is sending 21,500 extra American soldiers to Iraq, most of them to Baghdad for the offensive. Petraeus has asked for all extra forces to be deployed as soon as possible. Casey had been a sceptic of troop increases. Petraeus was a top commander of the 2003 Iraq invasion and oversaw a new U.S. military manual on fighting insurgencies that stresses understanding politics, ethics and local culture. He has completed two Iraq tours.
