Radical Shiite cleric Muqtada al-Sadr’s militia has kidnapped 18 Iraqi police officers in hopes of using them as leverage to force authorities to free detained militants, police said Tuesday. The recent kidnappings took place as al-Sadr aides accused authorities of trying to arrest top officials from the cleric’s Mahdi Army. The new tensions appear to threaten a fragile cease-fire between the Mahdi Army and Iraqi authorities. Al-Sadr’s followers fought a two-month rebellion against U.S. forces in April that died down after a series of truces. But on Monday, U.S. Marines clashed with al-Sadr militiamen near the cleric’s house, and a woman and three other bystanders were killed.Full Story