(CNN) North Korea's lead negotiator in nuclear talks with the United States, Kim Yong Chol, is expected to arrive in Washington by the weekend, a potential sign the two countries are getting closer to finalizing plans for a second summit between President Donald Trump and Kim Jong Un.
Kim Yong Chol, Pyongyang's former spymaster who has served as Secretary of State Mike Pompeo's counterpart in talks with the United States, is expected to arrive in the US capital Thursday and spend the night there, according to two US sources familiar with the negotiations.
Kim is then expected meet Pompeo and US special representative to North Korea Steve Biegun on Friday, the sources said.
It's unclear if he will visit the White House, but the sources say that is the expectation from the North Koreans and the US side is preparing for the possibility.
The dates for meetings between North Korea's top negotiator and US officials in Washington have only been confirmed to CNN by the US side. A source familiar with US-North Korea denuclearization talks told CNN that the meetings will happen "by this weekend." No firm details have been publicly announced yet.
"A lot of positive things are happening. He (Trump) and Chairman Kim have established a good relationship, and conversations between the United States and North Korea continue," a White House spokesperson told CNN.
"We are working to make progress on our goal of achieving the final, fully verified denuclearization of North Korea, and the President looks forward to meeting Chairman Kim again at their second summit at a place and time yet to be determined."
The location and the date of the second summit are expected to be discussed during the meeting in Washington, which comes after Trump and Kim Jong Un exchanged letters earlier this month.
Trump wrote that the United States was hoping for a second summit and would consider Bangkok and Hanoi as possible locations. The North Koreans have not yet told the United States if they will agree to either.
Kim Yong Chol last came to the United States in June. He visited New York and met with Pompeo before traveling to Washington, where he delivered an oversized envelope containing a letter from Kim Jong Un to Trump in the Oval Office. The two met for two hours in the White House.
During that visit, Kim was able to break the impasse between Washington and Pyongyang and help get the first US-North Korea summit back on track.
Experts say Kim's current trip is likely a step in the same direction.
"These meetings should be seen for what they are, a testing out of each other's positions on denuclearization to see if a summit is viable for both sides -- nothing more, nothing less," said Harry J. Kazianis, the director of defense studies at the Center for the National Interest, a Washington-based think tank.
This is Kim's second trip outside North Korea this year. He accompanied his boss to Beijing for a meeting with Chinese leader Xi Jinping last week. It was Kim Jong Un's fourth trip to China in less than a year, which state media from both countries touted as a sign of warming relations between the longtime allies.
Neither leader publicly addressed the possibility of a second meeting between Trump and Kim.
Trump and Kim Jong Un's summit in Singapore in June ended with a commitment from Kim Jong Un to "work toward complete denuclearization of the Korean Peninsula," but negotiations appear to have stalled since then.
North Korea refrained from carrying out any nuclear or missile tests in 2018 and has taken symbolic steps toward denuclearization, such as shuttering a missile test facility and destroying parts of its nuclear test site, Punggye-ri.
But it "has demanded what it calls 'corresponding measures' -- widely interpreted as some sort of sanctions relief -- for any big concessions on its nuclear weapon or missile programs," Kazianis said.
Many critics accuse the Trump administration of failing to get Pyongyang to agree to specifics at their first summit. They say the North Koreans are holding out for a second summit because they believe they can extract greater concessions by meeting with Trump directly, as opposed to working with envoys like Pompeo or Biegun.
"Pyongyang is clearly dissatisfied with what it has been hearing from Secretary Pompeo and other senior US officials and is eager to go over the heads of the President's aides in order to engage directly with President Trump," Evans Revere, a former US principal deputy assistant secretary of state for East Asian and Pacific affairs, says in a forthcoming paper to be presented in Seoul on Wednesday.
"The current impasse in denuclearization talks is the product of a US demand that North Korea take specific denuclearization steps, together with the DPRK's (Democratic People's Republic of Korea) insistence that the Singapore agreement is about improving relations and removing the US threat."