'Real progress' made with North Korea toward denuclearisation: Pompeo

The US has made a "real progress" with North Korea toward the denuclearisation of the Korean peninsula but still there is a long way to go, Secretary of State Mike Pompeo said on Tuesday.

Pompeo, who met North Korean leader Kim Jong Un on Monday in Pyongyang to discuss a future summit, told reporters that the two countries are back on a path toward denuclearisation.

"While there's still a long way to go and much work to do, we can now see a path to where we'll achieve the ultimate goal, which is the full and final verified denuclearisation of North Korea," Pompeo told reporters at the White House after a lunch with President Donald Trump.

Pompeo returned from a Asia trip Monday night, during which travelled to Japan, South Korea, North Korea and China.

Pompeo's trip was intended to set the table for a second summit between Trump and Kim, who held an historic summit in Singapore on June 12.

On Indian-American Nikki Haley resigning as the US Ambassador to the UN, Pompeo said she was his "great partner.

"I want to thank Amb Haley for the good work that she has done. She has been a great partner of mine for the five months that she and I have been working together, Pompeo said.

I want to wish her very well whatever comes next for her, Pompeo said.

In a surprise move, Haley on Tuesday resigned as the US Ambassador to the United Nations, becoming the latest casualty in the dysfunctional Trump administration just weeks before the crucial mid-term elections.