Secretary of State Rex Tillerson will press the tougher new US line on North Korea during talks in China on Saturday with the big powers split over how to rein in nuclear-armed Pyongyang.

The Trump administration has used Tillerson's Asia tour to break with years of strategic patience over North Korea, which the secretary of state said during a stop in Tokyo had "failed."

In Seoul on Friday, Tillerson said military action by the United States against North Korea was "on the table" if threats from the rogue regime escalate.

The sea change in US policy follows two North Korean nuclear tests last year and missile launches including a salvo earlier this month that Pyongyang described as a drill for an attack on US bases in Japan.

China, however, is deeply wary of the new US tack towards its volatile neighbour.

It called last week for the North, the United States and its ally South Korea to take steps to defuse tensions in hopes of re-starting diplomatic efforts to dismantle Pyongyang's nuclear and missile programmes.

Year of diplomacy, however, failed to deter North Korea's weaponisation and Washington has rebuffed the Chinese proposal.

Raising the pressure

Tillerson, a former Exxon oil executive who until now had adopted a low profile in office, meets Foreign Minister Wang Yi at 2:30 pm (0630 GMT) and later China's top foreign-policy official, Yang Jiechi.

Plans also are in the works for Tillerson to meet Sunday with President Xi Jinping as Beijing and Washington negotiate a possible first summit between Xi and Trump in April in the United States.

China is the last country with significant leverage over the isolated North Korean regime headed by Kim Jong-Un and Tillerson is expected to press it to use that clout.

On Friday, President Donald Trump accused China of foot-dragging in an Twitter post.

"North Korea is behaving very badly. They have been 'playing' the United States for years. China has done little to help!" he said.

Beijing shares US concerns over Pyongyang's nuclearisation, but also fears squeezing its economically backward neighbour too hard, lest it provoke a messy regime collapse.

China insisted Thursday its latest proposal -- for North Korea to suspend nuclear and missile activities in return for the US and South Korea halting military exercises that rile Pyongyang -- was the "only feasible plan."

"If the US or another country has a better plan, a better proposal, they can bring it out," a foreign ministry spokeswoman said.

At a joint press conference Friday with his South Korean counterpart Yun Byung-Se, Tillerson said "we are exploring a new range of diplomatic, security, economic measures".

Under the Obama administration, the US ruled out diplomatic engagement until Pyongyang made a tangible commitment to denuclearisation, hoping that internal stresses in the isolated country would bring change.

North Korea says it needs to be able to defend itself, and conducted its first underground atomic test in 2006 despite global opposition. Four more test blasts have followed.

The United Nations has imposed multiple sets of sanctions but China is accused of not fully enforcing them.

Beijing and Washington also are clashing over the deployment of a US anti-missile system to South Korea.

Washington and Seoul insist it is for purely defensive purposes, but Beijing says it undermines its own security and has reacted angrily, imposing a series of measures seen in South Korea as economic retaliation.