Washington (CNN) While Secretary of State Mike Pompeo's recent meetings with North Korean leader Kim Jong Un were billed primarily as diplomatic missions, the face-to-face encounters have also served as valuable intelligence gathering opportunities that are helping shape US officials' understanding of the reclusive dictator and guide ongoing talks between the two countries.

A series of constantly updated US intelligence assessments have determined that Kim will come to the negotiating table with his own red lines revolving around a single calculation: How much, if any, of his nuclear weapons program does he give up while still assuring the survival of his regime and his singular position in power?

These intelligence assessments, largely led by the CIA's Korea Mission Center, are examining all issues that could impact Kim's thinking and approach to the negotiations, including the impact of US-backed economic development and how Kim can maintain the loyalty of his top military commanders. The issue of Kim's concern for his safety and survival was even addressed by President Donald Trump in public comments when he guaranteed Kim's safety if he agreed to denuclearize.

The US intelligence community has been working to understand what makes Kim tick since he took power in 2011 -- gathering details related to his psychological makeup, leadership style and personality in order to support the policymakers tasked with dealing with North Korea's nuclear weapons program.

And that effort has only been amplified in recent weeks as US officials continue to lay the groundwork for on-again, off-again talks between Kim and Trump in Singapore on June 12.

Despite Trump's threat last week to call off the summit , the White House has indicated that preparations are still under way.

Representatives from Washington and Pyongyang have been dispatched in recent days to conduct various meetings, and in his most significant gesture so far, Kim sent his former intelligence chief and close confidante Kim Yong Chol to New York to meet with Pompeo.

Pompeo meets with Kim Yong Chol in New York, Wednesday, May 30.

Even after Trump made his cancellation announcement, Pompeo has continued to work on preparations for a potential summit. Defense Secretary James Mattis has also continued to publicly emphasize diplomacy led by Pompeo.

Those familiar with Pompeo's thinking have said that his meeting with Kim Yong Chol will set some of the terms and agenda for a potential summit -- but most importantly Pompeo loyalists believe the meeting is a sign that he is the senior US official, short of the President, that Kim is willing to work with.

A photo posted to Pompeo's official Twitter account showed the North Koreans dining on a meal of "steak, corn and cheese."

If Pompeo is included at the summit table, his role will include ensuring both Kim and Trump keep to the agenda and do not get unduly distracted by their rhetoric, one US official said.

"Secretary Pompeo has spent more time with the 'living God' than any other American ... (Kim) has been sheltered from foreign view very deliberately up until now," Nick Eberstadt, American Enterprise Institute scholar and adviser to National Bureau of Asian Research, told CNN.

While sources have relayed various rumors about Kim to intelligence officials over the years, Eberstadt said the US can be most confident in assessments regarding North Korea's "objectives because those haven't really changed between three generations of Kims."

On the same page?

While US intelligence officials have determined Kim is unlikely to completely surrender his nuclear program as part of a negotiation with the US, Trump has laid out a red line of his own -- saying any summit must include a guarantee that North Korea's weapons can no longer threaten the US or its allies.

But a series of US intelligence assessments have concluded that while Kim could give up some weapons including warheads and missiles, he may not be willing to give up his capabilities to regenerate his program.

That would include keeping scientific, engineering and technical capabilities and personnel which would be seen by Kim as his insurance policy to ensure he could stay in power, officials said.

"He is not going to do anything that allows him to become vulnerable," one official told CNN. He also could decide to keep some hidden weapons inventories, officials acknowledged.

So far, US officials say, the Kim regime hasn't taken any steps on denuclearization that could not be readily reversed. They said the May 24 destruction of underground tunnels to test nuclear devices was a "serious gesture." But it "doesn't foreclose further testing" at other locations, one official said.

US satellite imagery recorded technical equipment and gear being removed from the site prior to the destruction of the tunnels, three US defense officials say. "They are not going to give up anything valuable," one official said.

In addition the US has preliminarily identified other potential sites where the North Koreans could dig new underground tunnels for testing.

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Kim a 'rational actor' with his position largely set

Intelligence assessments have concluded that Kim is coming to the table with his position largely set with regards to what he will give up and what he plans to retain or possibly hide away.

It's not clear what security guarantees the US could give Kim that would convince him to give up his entire program, including those scientific, engineering and technical capabilities including underground sites that could shield key items.

That idea is largely supported by the US intelligence community's assessment that Kim is a "rational actor" motivated by the survival of his own regime.

Pompeo, who took a leading role on the North Korea issue even before he was confirmed as secretary of state, has had direct contact with Kim on two occasions -- providing unique insight into the isolated leader's personal makeup that also supports the latest findings from the intelligence community.

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"My personal view is that the assessment hasn't changed: he's a rational actor who has consolidated power; he's in control," said Ambassador Joseph R. DeTrani, who previously served at the Department of State as the special envoy for Six-Party Talks with North Korea.

A former intelligence official specializing in Asia who maintains contact with current officials told CNN: "I'm sure (CIA) would stick by the line that Kim just wants to die peacefully of old age."

The CIA did not respond to CNN's request for a comment.

But Pompeo himself has said that the meeting not only supported the intelligence community's existing assessment, but that Kim's behavior indicated he was sincere about pursuing a path toward denuclearization.

"I did get a sense that he was serious," Pompeo said.

"The economic pressure that has been put in place by this global effort that President Trump has led has led him to believe that it is in his best interests to come to the table and talk about denuclearization," he added.

Currently the highest-ranking US administration official to meet with Kim, Pompeo's observations support the idea that Kim is not irrational or crazy -- an image that has been perpetuated at times by the media, some lawmakers and even President Trump himself, according to Bruce Klingner, a former deputy division chief for Korea at the CIA who's now a senior fellow at the Heritage Foundation

"He was painted as someone who the US could not count on to not start a war," Klingner said. "We are seeing some of that now as people realize that Kim, contrary to perception, is not crazy or irrational."

Value of direct contact

North Korea's history of isolation has traditionally forced US intelligence agencies to utilize second-hand information gathered through interviews with individuals who have had direct contact Kim during his life.

Analysts try to put together a profile of a leader based on readouts from people who have met with them and reading about them to get a sense of their psychology and how they make decisions, Klingner said.

With an isolated leader like Kim, intelligence is rarely collected directly from the source, making Pompeo's contact so valuable.

"Having Pompeo in a room with Kim provides direct contact and offers insight into Kim's mannerisms, how capable he is as a leader, and how much he relies on others," according to Klingner.

"Having direct access to someone should provide a lot better insight," he said.

Pompeo is not specifically trained to interpret body language indicators or other subtle details that may have presented themselves in these meetings, but he was accompanied by intelligence officials who were taking note of these cues, a source familiar told CNN.

Two US officials have told CNN that Kim was very straightforward, professional, calm and on top of his brief in his meeting with Pompeo, adding that he knew and could discuss the issues in detail.

And one source briefed on the matter told CNN that it was clear to Pompeo that Kim understands how to present himself as a fairly normal politician.

But while those who meet with Kim often determine he is not necessarily insane, Klingner warned that the difference between those misconceptions and the impression Kim gives off in person can also lead to an overreaction.

"When someone meets with Kim, they often come back sort of in awe -- realizing that he is not the crazy guy in the basement -- and with the conclusion that the US can deal with him," he said.

"But due to the fact that they often go into the meeting with a misconception of Kim based on caricatures from outside intelligence community, the perceptions often shifts from one extreme to another," he added.

Pompeo, however, has expressed a sense of cautious optimism about Kim's intentions.

Even after Trump threatened to cancel the scheduled summit last week, Pompeo said he was "hopeful" discussions could get back on track, adding there was "little doubt" in his mind that Kim understood the scope of what the US was asking for with regards to the permanent denuclearization of the Korean Peninsula.

He has also cautioned that North Korea has made and broken promises in the past.

"President Trump has made clear we are going to work to get a meeting set up, the two of them will meet. In the event it fails, respectfully, President Trump will walk away and the pressure will remain but in the event we reach a resolution it would be a wonderful thing for the world," Pompeo said last week after Trump threatened to cancel the summit.

One source with knowledge of the situation told CNN that while some progress has already been made to this point, there is still a general understanding within the administration that the North Korean regime remains unpredictable -- as it has been for decades.

And despite Pompeo's assurances that he believes Kim is serious about wanting to negotiate, some within the administration remain deeply skeptical about North Korea's intentions -- specifically their willingness to give up their nuclear weapons, the source said.

Trump the wild card

It remains unclear as to how Trump is personally preparing for the potential sitdown with Kim, but he has told advisers he's confident in his ability to sway the North Korean leader in person.

But the President's push for a face-to-face meeting with Kim is raising concerns that he may disregard the vast intelligence resources provided on Kim in favor of leaning on his own instincts.

An intelligence profile of Kim is provided for Trump in his daily briefing, according to DeTrani, but it remains unclear as to whether the President regularly reads intelligence reports provided to him.

"That profile includes intelligence related to Kim's personality, negotiation tactics, personal history and potential weaknesses so that the President might be able to anticipate certain moves once they are in the same room," DeTrani said.

Ultimately, intelligence analysts are trying to enable policymakers to make the most informed decisions possible, but "at the end of the day, you can lead a horse to water but you can't force someone to read the briefing," according to Klingner.

"Trump has thrown out the usual diplomatic playbook and the concept of bureaucratic timelines," Klingner said. "Traditionally, the US would not deploy a president to negotiate terms but to sign the agreement once the details were in place."

"Trump doing the opposite, implementing a top-down approach," he added. "He's not going to go through tons of background materials or meetings with experts but instead, as he wrote in Art of the Deal, goes with his gut."