Asia tour presents challenges for US secretary of state

The top American diplomat Rex Tillerson is heading to East Asia, where he’ll stop in Japan, South Korea and China.

He’s making his first official tour of the region at a time of heightened tension over North Korea’s nuclear and missile programmes.

Donald Trump promised while campaigning for the presidency to get tough on Pyongyang’s ally, China.

Now the question is – will Tillerson follow through?

Al Jazeera’s State Department correspondent Patty Culhane reports from Washington DC.