North Korean official heads to Washington with Kim's letter

Kim Jong-un's emissary is heading to Washington with a letter from the North Korean leader to US President Donald Trump after two days of talks here with Secretary of State Mike Pompeo that has brightened the chances of a summit between the two leaders.

"I am confident we are moving in the right direction," Pompeo said on Thursday at a news conference here after his talks with Kim Yong-chol, the North Korean leader's representative.

In a sign that the US and North Korea have made progress towards holding the historic summit in Singapore on June 12 after Trump had abruptly called it off last week, the New York negotiations were wrapped up two hours early.

Pompeo said: "We had a set series of items that we wanted to make sure we covered, topics which we made sure that we were clear on in terms of what our expectations were and their expectations in return of us. We achieved that."

Speaking to reporters earlier on Thursday at the Andrews Air force Base near Washington, Trump said that the talks in New York had been "very positive", adding "I look forward to seeing what's in the letter. But it's very important to them".

The talks started in New York because North Korean diplomats are barred by the US from traveling 40 km beyond the city and Kim Yong-chol needed an exemption to go to the capital.

Even after Trump said he was withdrawing from the summit citing Pyongyang's "tremendous anger and open hostility", the two sides have resumed talks in Singapore, the demilitarised zone on the border between the two Koreas and in New York in hopes of salvaging what would be a historic achievement for Trump.

Kim Jong-un appears to be invested in the denuclearisation talks that could translate to economic development for his impoverished country that is under severe economic sanctions.

While sounding optimistic, both Trump and Pompeo also left open the possibility that the summit could hit the rocks again.

Asked by a reporter if there would be a confirmation on Friday that the summit will take place, Pompeo replied: "(I) Don't know."

"This is going to be a process that will take days and weeks to work our way through," he said of a denuclearisation deal. "There will be tough moments, there will be difficult times."

The two leaders will go to the summit "with their eyes wide open and with a clear understanding of the possibilities for the future", he added.

Trump also laid out the possibility that if the Singapore summit took place it may not have a definite outcome but could be the start of drawn-out negotiations.

"I want it (Singapore talks) to be meaningful. It doesn't mean it gets all done at one meeting; maybe you have to have a second or a third," he said.

This could mean that Trump was willing to meet Kim initially without a firm agreement on denuclearisation, which had been a pre-condition.

Pompeo, however, said that in the talks with Kim Yong-chol: "I have been very clear that President Trump and the United States objective is very consistent and well known: the complete, verifiable, and irreversible denuclearisation of the Korean Peninsula."

Pompeo and Kim Yong-chol are both former heads of their nations' intelligence services.

With Pompeo taking the lead in the negotiations, Trump's newly appointed National Security Adviser John Bolton has been sidelined.

Bolton's suggestion of a "Libyan model" in denuclearising North Korea brought the "tremendous anger and open hostility" that Trump referred to while cancelling the summit last week.

Muammar Gaddafi shut down his nuclear programme and handed over some elements of it to the US, but he was overthrown in 2011 after Washington and its European allies attacked Libya.