"US will act calmly" - S Korea's Moon

The President of South Korea, Moon Jae-in, has called for the increasingly bitter dispute between the United States and North Korea to be resolved peacefully. After a week of incendiary language between President Trump and Kim Jong Un over the threat of a missile strike on the US territory of Guam, and Pyongyang's increasing nuclear capabilities, tensions have escalated in the region. Kathryn Ryan talks to Evans Revere a former high ranking State Department official who has participated in negotiations with North Korea.