WASHINGTON — Secretary of State Mike Pompeo is heading to North Korea on Thursday with the hopes of firming up a plan to dismantle Kim Jong Un's nuclear weapons program.

In what will be his fourth meeting with North Korean officials in three months, the trip comes amid reports citing U.S. intelligence officials that Pyongyang does not intend to give up its nuclear weapons program and is actively working to deceive the U.S.

Pompeo is expected to have a day and a half of meetings on this third visit to North Korea and make his first overnight stay in the country.

The secretary of state also plans to travel to Tokyo to meet with Japanese officials before continuing on to Vietnam, the United Arab Emirates and finally Belgium to meet President Donald Trump at the NATO Summit next week.

Declining to speak on intelligence matters, State Department spokesperson Heather Nauert told reporters last week: "We're in a good spot. We're all keeping a close eye. The secretary has been very clear and very blunt with the North Koreans about what he expects."

The meetings Thursday will be the highest-level discussions between the U.S. and North Korea since the historic summit between Trump and Kim in Singapore last month.

On our way to #DPRK for ⁦@SecPompeo⁩ ‘s next round of consultations. We are committed to the denuclearization of North Korea, as outlined by @potus & Chairman Kim at Singapore Summit @statedept pic.twitter.com/STI6cxiMk1 — Heather Nauert (@statedeptspox) July 5, 2018

There, the two leaders signed a joint statement agreeing to "work toward denuclearization of the Korean Peninsula," but the document included no details on the location of the nuclear weapons program, how it would be dismantled or how that dismantling would be verified.

Trump declared shortly after his return from Singapore "there is no longer a Nuclear Threat from North Korea," and "the problem is largely solved," and tweeted recently: "Trump Many good conversations with North Korea — it is going well! In the meantime, no Rocket Launches or Nuclear Testing in 8 months. All of Asia is thrilled. Only the Opposition Party, which includes the Fake News, is complaining. If not for me, we would now be at War with North Korea!"

But, as first reported by NBC News, U.S. intelligence officials believe that the North Korean government continues to expand its nuclear weapons activities, increasing production of fuel for nuclear weapons at multiple secret sites in recent months. The officials also said Kim may try to hide those facilities as he seeks more concessions in nuclear talks with the Trump administration.

In an interview with CBS on Sunday, national security adviser John Bolton said Pompeo would discuss with the North Koreans "how to dismantle all of their WMD (weapons of mass destruction) and ballistic missile programs in a year."

The State Department said the U.S. will not provide a timeline.

"I know some individuals have given timelines; we're not going to provide a timeline," Nauert said Tuesday. "A lot of work is left to be done. Certainly, we go in eyes wide open, with a very clear view of these conversations."

Gordon G. Chang, author of "Nuclear Showdown, North Korea Takes on the World," told MSNBC's Steve Kornacki last week that success for Pompeo would be receiving a document outlining the complete denuclearization of the Korean Peninsula.

"Anything short of that is basically, I think, essentially the North Koreans just sort of trying to drag this process out," Chang said.

Former U.S. ambassador to North Korea, Christopher Hill, said Pompeo bringing home such document would be more than success.

"It would be Christmas," Hill said. "But the reality is they are not going to get those things."