As it reaches its closest point to earth. President Trumps National security advisor, says north Koreas Nuclear ambitions pose the greatest threat to the United States, and to the world. The comments from hr mcmaster come on the eve of the largest ever joint military exercise in the region between us and south korean airforces. Pyongyang has called the drill an all out provocation. From washington, laura bicker reports. Weapons experts have described the latest north Korean Missile as a beast, capable of striking the us mainland. There were celebrations in pyongyang, a staged event to declare that north korea is becoming a nuclear nation. This is something the Trump Administration has said it will not accept. The greatest immediate threat to the United States, and to the world. Speaking at a defence forum, the us National Security adviser had this warning. China has tremendous coercive economic power over north korea. You cannot shoot a missile without fuel. There are ways to address t