NAJAF, Iraq - The forces of anti-U.S. cleric Muqtada al-Sadr in this holy Shiite city and neighboring Kufa braced Saturday for an American assault, with hundreds of men with assault rifles roaming the streets and guarding makeshift checkpoints. In anticipation of violence and because of a major religious occasion this weekend, most stores in Najaf and Kufa were closed. Some owners emptied shops of goods, storing them at home for fear of looting amid any violence, residents said. No police or coalition troops from the Spanish contingent in charge of security in the two cities could be seen. U.S. commanders...