America's new ambassador to Iraq expressed horror Tuesday at the violence wracking the country and said Islamic extremists and Saddam Hussein loyalists are trying to start a civil war. U.S. Ambassador Zalmay Khalilzad, who arrived from Afghanistan, said militants are using Iraqis as "cannon fodder" in a quest to dominate the Islamic world. "I will work with Iraqis and others to break the back of the insurgency," Khalilzad promised on a day that saw more than a dozen gunmen launch an assault on a Baghdad police station, wounding two policemen.