U.S. forces arrest a key aide to radical cleric Muqtada al-Sadr and wage battles with militia loyal to the Shiite leader. The aide, Riyadh al-Nouri, was taken captive at a house in Najaf. He is al-Sadr's brother-in-law. An Army spokesman said a "very large number" of youths — members of al-Sadr's militia — were killed in fighting in Najaf and Sadr City. NPR's Peter Kenyon reports.