Kim Yong-chol will also meet US Secretary of State Mike Pompeo on Thursday or Friday, and both sides are fine-tuning details, South Korean news media said, citing sources familiar with the talks.

Senior North Korean official Kim Yong-chol reportedly bound for Washington

North Korea’s Vice Foreign Minister Choe Son-hui meanwhile arrived in Beijing on Tuesday on her way to Sweden to attend an international conference, sparking media speculation that she may meet her US counterpart, Stephen Biegun, special representative for North Korea, in order to discuss details of the Washington talks.

“I will talk to you when I get there,” Choe told journalists at the airport in Beijing.

South Korea’s Kyunghyang daily, citing a diplomatic source, said Choe and Biegun will work on the wording of a possible agreement between the US and Pyongyang, setting a broad road map for US-North Korea dialogue.

This month, Trump said he had received a “great” letter from Kim Jong-un and would probably meet him again in the not-too-distant future, as part of efforts to persuade him to give up his nuclear weapons.

How Pyongyang is taking advantage of rift between Tokyo and Seoul

Pompeo made several trips to Pyongyang last year, but the two sides did not reschedule an abruptly cancelled November meeting between him and Kim Yong-chol that aimed at pave the way for a second presidential summit.

“The reason that the November meeting was scrapped was that Kim Yong-chol’s request for a meeting with Trump was not accepted”, a South Korean government source was quoted as telling the Kyunghyang daily.

“The North has strongly demanded this time that Kim should meet Trump,” he said.

Pyongyang calls for direct communication between the two leaders instead of going through US bureaucrats who it believes are set on a hard line towards Pyongyang, hampering progress.

Washington and Seoul have been discussing potential US measures to reciprocate North Korea’s possible steps toward denuclearisation, which could include dismantling the Yongbyon main nuclear complex or intercontinental ballistic missiles (ICBMs) aimed at the US, South Korean officials said.

Potential corresponding action by the US includes exemptions from sanctions on inter-Korean business and tourism, and opening a liaison office as a prelude to a formal launch of diplomatic relations, Seoul officials said.

“Those ideas are being discussed as interim measures, not as an end state, in order to expedite the denuclearisation process because the North wouldn’t respond to any demand for a declaration of facilities and weapons,” a senior South Korean official said, requesting anonymity due to the sensitivity of the matter. “The end goal remains unchanged, whether it be complete, verifiable and irreversible denuclearisation, or final, fully verified denuclearisation.”

The official said a second summit between Trump and Kim might happen in late February or early March, though: “No one knows what Trump is thinking.”

Kim renewed his resolve to meet Trump again during his meeting with Chinese President Xi Jinping in Beijing last week.

“At the second summit, they’ll probably focus on reaching a possible interim deal rather than a comprehensive road map for denuclearisation,” said Cheong Seong-chang, a senior fellow at South Korea’s Sejong Institute. “Whether Pyongyang is willing to abolish ICBMs, in addition to disabling the Yongbyon complex, would be key, and if so, the North is likely to demand sanctions relief in return.”

Additional reporting by Reuters