A U.S. diplomat will visit Pyongyang this week to try to advance a stalled deal under which North Korea promised to disclose all its nuclear programs and eventually abandon them, a U.S. official said on Monday. The U.S. official, who asked not to be named, said Sung Kim, the director of the State Department’s Office of Korean Affairs, was expected to make stops in Seoul on Tuesday and in Beijing on Wednesday before visiting Pyongyang on Thursday. Full Story