US Secretary of State Mike Pompeo. (File Photo: AP)

US Secretary of State Mike Pompeo headed to Pyongyang Sunday for new talks with Kim Jong-Un on denuclearisation and a second US-North Korean summit.

Pompeo departed from Tokyo, where he spent the first leg of a tour that will include stops in Pyongyang, South Korea and China.

"Next stop Pyongyang to meet with Chairman Kim and continue our work to fulfil the commitments made (by) POTUS and Chairman Kim," Pompeo tweeted, using an acronym to refer to US President Donald Trump.

The trip will be Pompeo's fourth to Pyongyang, as the contours of a possibly historic US-North Korea deal take shape.

On the flight to Tokyo, Pompeo said his aim was to "develop sufficient trust" between Washington and Pyongyang to inch towards peace.

"Then we are also going to set up the next summit," said Pompeo.

However, he played down expectations for a major breakthrough.

"I doubt we will get it nailed but begin to develop options for both location and timing for when Chairman Kim will meet with the president again. Maybe we will get further than that," said the top US diplomat.