On his trip to Asia, Secretary of State Rex Tillerson cut short his visit with South Korean officials due to "fatigue." That's according to the Korea Herald. Tillerson has not allowed American reporters to travel with him, but in a rare public appearance, he said called on North Korea to "abandon its nuclear and ballistic missile programs and refrain from any further provocations. The US commitment to the defense of Japan and its other treaty allies through the full range of our military capabilities is unwavering. "
That's been widely interpreted as a threat of "pre-emptive action," although Tillerson did not use those words. Nicholas Burns was ambassador to NATO and undersecretary of state for political affairs during the George W. Bush Administration. Bow a professor at Harvard's Kennedy School of Government, Burns says Tillerson's may have addressed North Korea but he's talking tough to get the full attention of the Chinese government.