North Korea dominates Rex Tillerson's trip to Asia

US Secretary of State Rex Tillerson continues his visit to Japan, South Korea and China. Top of the agenda is defence, prompted by the regional tensions surrounding North Korea's ballistic missile and nuclear weapons programmes.

Complicating matters is Chinese opposition to an American missile defence system based in South Korea, as well as Donald Trump's tweets criticising the region's dominant power for not doing enough to rein in its rogue ally.