U.S. and South Korean officials in Pyongyang agree on a nuclear test . March 2013 . North Korea warns workers in South Korea to leave , with similar advice to China . North blocks workers from entering joint commercial facilities operated with South .
U.S. and South Korean officials in Pyongyang agree on a nuclear test . North Korea warns workers in South Korea to leave , with similar advice to China . North blocks workers from entering joint commercial facilities operated with South .