After shoring up relations among friends and frenemies in East Asia, US Secretary of State John Kerry says America is ready to “reach out” to North Korea if it gives up nuclear weapons, while vowing to protect US allies.

Kerry was in Tokyo, following stops in Seoul and Beijing.  He said that North Korea has to take steps towards giving up its nuclear weapons program.

"They have to take some actions. Now how many and how much I want to have a discussion with folks back in Washington (about)... but they have to take action," said Kerry.

But standing alongside his Japanese counterpart, Fumio Kishida, Kerry also said the US will take whatever steps are necessary to defend its allies Japan and South Korea.

Earlier in Beijing, Kerry secured China’s cooperation to use its influence to get North Korea to calm down after weeks of threats and provocations, with both countries saying they are committed to "the denuclearization of the Korean peninsula in a peaceful manner".