HANOI, Vietnam — His intelligence chiefs warn that North Korea is unlikely to surrender its nuclear weapons. His advisers fret that a breakthrough could prove elusive and that he might make an impulsive concession to score headlines. And his allies around the world worry he could get easily outmaneuvered.

Yet, President Donald Trump is steadfast in his determination to meet face-to-face here this week with Kim Jong Un, aides say, because he has an unwavering faith in the power of the pen-pal relationship he has cultivated with the North Korean leader not only to bend the course of history, but to shape his own legacy.

"We have had such a great relationship," Trump said Friday. "If I were not elected president, you would have been in a war with North Korea."

The two men will enter their second summit together on Wednesday as unorthodox leaders who are both distrustful of the global establishment, eager to project dominance and determined to maximize their power.

They are worlds apart — Trump is a septuagenarian mogul who fancies himself capitalism's golden progeny; Kim is a millennial strongman whose ruthless rule leaves his citizens impoverished and his adversaries off-balance.

But since their historic first meeting in Singapore last June, the two leaders have each adopted a strategy of playing to the other's ego with gushing and gratuitous adoration in pursuit of their aims: For Trump, North Korea's denuclearization; for Kim, its economic revival and respect on the world stage.

Trump gloats about the half dozen or so letters Kim has written him as if he were a smitten teenager in possession of valentines from a crush. White House officials refer to the diplomatic correspondence jokingly as "love letters." Kim addresses Trump as "Your Excellency" and employs flowery language to describe the president's energy and political smarts, according to people who have read them. Trump has shown the documents to dozens of Oval Office visitors and bragged about them in public.

"He wrote me beautiful letters — and they're great letters," Trump said in September at a rally in West Virginia. "We fell in love."

At the United Nations General Assembly later that month, Trump waxed about his budding relationship with Kim: "He likes me, I like him. We get along. He wrote me two of the most beautiful letters. When I showed one of the letters — just one — to [Japanese] Prime Minister Abe, he said, 'This is actually a groundbreaking letter.'"

Trump continued, "It is a historic letter. It's a beautiful piece of art. And I think we're going to make a deal."

Trump has responded to Kim with his own mash notes, raving about how much he enjoys his company and vowing to make history together, according to White House officials who spoke on the condition of anonymity to describe private documents.

Although they credit Trump with forging a warmer rapport with the North Korean leadership than any other American president, experts in U.S.-North Korea relations are skeptical that the relationship will result in denuclearization or peace.

"Personal chemistry between leaders is clearly important," said Victor D. Cha, the top North Korea adviser in the George W. Bush administration.

But, he added, "Is that personal relationship enough to create success in the policy? We are so far apart that the notion that the friendship alone would create a North Korean decision to give up all of their nuclear weapons is very hard to imagine."

Absent from Trump's messaging on North Korea over the past year has been any mention of human rights. The savagery of Kim and his government has been well documented and was once a rallying cry for Trump. The president shared the story of Ji Seong-ho, a North Korean activist who defected to South Korea, in his 2018 State of the Union address as an emotional call to rid the world of tyranny and brutality.

But over the past year, Trump has said little publicly about Kim's barbarism, and officials said that in private the president has told confidants that he considers human rights in North Korea largely inconsequential to striking a denuclearization deal.

"Trump has really virtually no interest in the internal affairs — and human rights, in particular — of other regimes around the world," said Ian Bremmer, president of the Eurasia Group and a foreign affairs expert. "The transactionalism of Trump means that he is much more unfettered in being able to consider a back-and-forth with Kim Jong Un that no other leader would have. Returning salutes to a North Korean leader, for example, and talking about how much of a pal he is and how Kim Jong Un is smart. Trump doesn't talk about concentration camps and assassinations and mass starvation and forced labor."

Bremmer was referencing Trump's salute of a North Korean military general during the summit in Singapore, which was documented in a North Korean propaganda video and drew criticism in the United States.

In the run-up to the summit in Hanoi, Trump's advisers have credited his flattery of Kim with creating the potential for a peace deal. In a January speech at Stanford University, Stephen Biegun, the U.S. special representative for North Korea who has led on-the-ground preparations in Hanoi, listed the many stark differences between the United States and North Korea on a range of societal issues including human rights.

"Yet despite these many obstacles, we have managed to sustain engagement now for many months, largely due to the personal determination of President Trump and his consistent willingness to use voice and written word to send positive messages of trust and confidence to Chairman Kim and the North Korean leadership," Biegun said.

Administration officials over the weekend played down the notion of any final breakthrough in this week's negotiations. Secretary of State Mike Pompeo called denuclearization "a long and difficult task" in an interview on NBC's "Today."

Rather, administration officials said they expect Trump's second summit with Kim will produce incremental progress, including, perhaps, arriving at an agreed upon definition of denuclearization and laying out a timetable for future negotiations for North Korea to freeze its nuclear weapons and missile programs.

"The president's not in a hurry, particularly as long as things continue to move forward in a positive manner and as long as the conversations continue to go well," White House press secretary Sarah Sanders said on Fox News. "We'll see what happens. I think that the only one setting high expectations is probably the media because they're looking for reasons to attack this president. They hate the idea that he's done so well on something his predecessors couldn't do anything on."

Aides said Trump is planning to try to pitch Kim on his vision for economic prosperity in North Korea should the reclusive state open itself to the world. This is a theme he hit on in Singapore, where Trump said he complimented Kim on the country's topography and its potential as a resort destination.

"They have great beaches," Trump told reporters at the conclusion of the Singapore summit. "You see that whenever they're exploding their cannons into the ocean, right? I said, 'Boy, look at the view. Wouldn't that make a great condo behind?' And I explained, I said, 'You know, instead of doing that, you could have the best hotels in the world right there.' Think of it from a real estate perspective."

Trump has continued to play up North Korea's economic potential. He said earlier this month, "Their location between South Korea and then Russia and China — right smack in the middle — is phenomenal."

Even Trump's staunchest allies are tempering their expectations for the Hanoi summit.

"Everybody is in a trust-but-verify mode," said Rep. Mark Meadows, R-N.C., a confidant of the president. "It will be another summit with a list of to-dos. I think everybody is realizing it's a 60-year-old problem that's not going to be addressed in a year."

Since Singapore, the North Korean military has stopped testing its nuclear weapons and ballistic missiles, but according to U.S. intelligence assessments, it has done little else toward denuclearization.

"They've done exactly zero to create transparency" around their intercontinental ballistic missile and ballistic missile programs and "have not moved toward denuclearization," Bremmer said.

He added that he thought Pompeo and national security adviser John Bolton were "deeply skeptical the North Koreans will make such progress, but that doesn't mean Trump won't announce a deal."

Trump's aides did not push for a second summit with Kim so immediately, though officials said Trump was partially interested in staging one in February as a distraction from the 35-day federal government shutdown, which turned out to be a political blow for the president.

"You can suck all the oxygen up out of the entire room and captivate the entire world," said one Trump adviser, who spoke on the condition on anonymity to discuss internal deliberations, noting that Trump marveled at his relatively positive news coverage for days after the meeting in Singapore.

He sees his summits with Kim as television-ratings gold, aides said.

Aides have discussed with Trump that Kim is not a rational actor, and that he could be mentally unstable, according to a person present for those private conversations who spoke on the condition of anonymity to describe them.

In 2017, when the two leaders traded insults, White House officials explained to Trump that there was no predicting or controlling how Kim might respond or possibly retaliate, the person said. At the time, Trump mocked Kim as "Little Rocket Man," while Kim said Trump was a "mentally deranged U.S. dotard," a word suggesting senility.

The president's position then, according to the person, was "you have to deal with a bully by bullying them — and if someone is going to be tough, you've got to be more tough back."

Trump routinely asked in private meetings, "Why wouldn't I meet with him?"

He has supreme confidence in his ability to convince anyone to do anything, and he told his staff that North Korea would provide an opportunity for him to become a historic president, former aides said.

In the days before the summit in Singapore, Trump claimed he could size up Kim instantly. “My touch, my feel — that’s what I do,” the president said.

Their interactions were friendlier than most U.S. officials expected, with the young North Korean leader appearing personable and charismatic in Trump's presence. They have shared interests in Hollywood movies and basketball. (Former NBA star Dennis Rodman, who also appeared on Trump's reality show "The Celebrity Apprentice," has visited Kim in Pyongyang multiple times.)

At one point, as the two leaders walked around the lush island compound where they met, it appeared Kim was about to step into "the Beast," Trump's armored limousine.

"The president would have been fine with it," said one U.S. official in attendance who spoke on the condition of anonymity to describe the scene. "Everyone else was freaking out."

After several hours of meetings, Trump told reporters he was impressed by Kim.

“You’d be very surprised,” he said. “Very smart. Very good negotiator. Wants to do the right thing.”