BAGHDAD, Iraq - Troops flooded a Baghdad neighborhood in a new U.S. military offensive against guerrillas Sunday, as an audiotape purportedly made by Saddam Hussein (news - web sites) urged Iraqis to escalate their fight against the occupation. The U.S. military moves in Baghdad and elsewhere in Iraq (news - web sites) came as the Army tried to determine why two of its Black Hawk helicopters crashed in the northern city of Mosul, killing 17 soldiers in the worst single loss of American life since the war began. In its offensive, the military fired a satellite-guided missile with a 500-pound...