U.S. and Iraqi troops moved into a Sunni neighborhood in southern Baghdad on Thursday, while insurgents struck back with car bombs that killed seven people. In southern Iraq, British troops sealed off the border with Iran to prevent weapons smuggling. Helicopters buzzed overhead as a joint U.S.-Iraqi force headed into the Dora neighborhood — a longtime Sunni militant area — on the second day of a long-awaited security operation in the capital, according to Iraqi officials. U.S. troops searched three Shiite areas Wednesday, meeting little resistance in house-to-house searches. Full Story