Radical Shiite cleric Muqtada al-Sadr appeared in public for the first time in months on Friday, delivering a fiery anti-American sermon to thousands of followers and demanding U.S. troops leave Iraq. It was not immediately clear why he chose to return now to his base in the Shiite holy city of Najaf from Iran. His speech had new nationalist overtones, calling on Sunnis to join with him in the fight against the U.S. presence. He also criticized the government's inability to provide reliable services to its people. Al-Sadr's reappearance, four months after he went underground at the start of the...