Meanwhile, a review of American casualties in Iraq has further undercut the Bush administration’s claim that Iran is supplying bombs to Shiite insurgents that have targeted U.S. troops. McClatchy Newspapers is reporting 90 percent of U.S. casualties have come in Sunni areas. Some of those deaths were caused by explosively formed projectiles, or EFPs. The administration had suggested the EFPs were being used almost exclusively by Iranian-backed Shiite groups.