South Korea has asked to buy $4.2 billion worth of Patriot Advanced Capability-3 missile systems, according to the Defense Department. The potential foreign military sale was one of three announced by the Pentagon yesterday. The proposed sale to South Korea, if approved by Congress, would include 14 PAC-3 fire units complete with 71 launching stations, 14 radar sets, 14 engagement control stations, 31 antenna mast groups, 14 electric power plants, 616 missiles, 313 Single Channel Ground and Airborne Radio Systems...