U.S. administrators in Iraq declared a radical Shiite cleric an “outlaw” Monday and announced a warrant for his arrest, heightening a confrontation after battles between his supporters and coalition troops killed at least 52 Iraqis and nine coalition troops, including eight Americans. American officials would not say when they would move to arrest Muqtada al-Sadr, who is holed up in the main mosque in Kufa, south of Baghdad, guarded by armed supporters. “We don’t fear death and martyrdom gives us dignity from God,” said al-Sadr, a 30-year-old firebrand who has frequently denounced the U.S. occupation in his sermons.