U.S. Department of Defense: ‘Coordination of U.S. nuclear weapons in Korea’, Yoon Seok-yeol’s ‘nuclear-based all-in-one’ conflict While the U.S. Assistant Secretary of Defense ruled out the 'integral type' in the joint guidelines of the Nuclear Consultative Group (NCG) at the ROK-U.S. summit in Washington as 'coordination of limits to Korea's conventional support to U.S. nuclear weapons' regardi..