SINGAPORE (CBSNewYork/AP) — With a long handshake and a pair of smiles, President Donald Trump and North Korean leader Kim Jong Un opened an unprecedented summit in Singapore, reaching for an ambitious deal to resolve global concerns about the isolated nation’s nuclear weapons program.

In the first meeting of a sitting U.S. president and a North Korean leader, Trump and Kim converged at a luxury resort on Singapore’s Sentosa Island, clasping hands as they stood on a red carpet in front of a backdrop of alternating U.S. and North Korean flags.

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Trump was first to arrive at the summit site, followed by Kim, both readying for the 9 a.m. meeting that culminated dizzying weeks of negotiations over logistics and policy.

“We are going to have a great discussion and I think tremendous success. We will be tremendously successful,” Trump said.

Speaking through an interpreter, Kim said: “It wasn’t easy for us to come here. There was a past that grabbed our ankles and wrong prejudices and practices that at times covered our eyes and ears. We overcame all that and we are here now.”

Trump and Kim met privately for roughly 45 minutes before aides to each joined for more discussions and a working lunch.

“We’ll solve the big problem, the big dilemma that until this point has been unable to be solved,” Trump said. “Working together we will get it taken care of.”

But even before they met, Trump announced plans to leave early, raising questions about whether his aspirations for an ambitious outcome had been scaled back.

Up early in Singapore, Trump tweeted with cautious optimism: “Meetings between staffs and representatives are going well and quickly … but in the end, that doesn’t matter. We will all know soon whether or not a real deal, unlike those of the past, can happen!”

In the run-up to the talks, Trump had hopefully predicted the two men might strike a nuclear deal or forge a formal end to the Korean War in the course of a single meeting or over several days. But on the eve of the summit, the White House unexpectedly announced Trump would depart Singapore by Tuesday evening, meaning his time with Kim would be fairly brief. And Secretary of State Mike Pompeo sought to keep expectations for the summit in check.

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“The complete verifiable denuclearization of the Korean peninsula is the only outcome that the United States will accept,” he said.

Pompeo added that Trump, “recognizes Chairman Kim’s desire for security” and his interest in economic development. He said the president was willing to help the North achieve both if it “makes the right choices,” CBS News reported.

The president arrived in Singapore on Sunday, meeting with Prime Minister Lee Hsien Loong ahead of the main event with Kim, tweeting “Great to be in Singapore, excitement in the air!”

The president had lunch Monday with Lee and other officials from Singapore, who gave him a birthday cake ahead of Trump’s 72nd birthday Thursday.

“You’re my friends,” Trump said. “We’ve got a very interesting meeting in particular tomorrow, and I think things can work out very nicely.”

Kim arrived earlier Sunday, his motorcade at times surrounded by a jogging security team. He also met with Singapore’s prime minister, thanking him for hosting the summit and telling him “the entire world is watching.”

The president has said his administration’s goal is complete denuclearization of the Korean peninsula, but in recent weeks, the White House has tried to temper expectations.

“I’ve said many times, ‘who knows, who knows.’ It may not work out. It’s a good chance it won’t work out,” Trump said. “There’s probably an even better chance that it will take a period of time. It will be a process.”

Korean affairs expert John Delury says the summit is both risky and unprecedented for Kim. North Korea has a crippled economy, where many live in poverty and deal with food shortages.

“The North Korean system is predicated on hostility and what Kim Jong Un is doing is he’s going way out of that comfort zone,” he said.

Kim has promised his people a revitalization of their economy and a plan to make the country a tourist destination, both of which are nearly impossible because of strict international sanctions.

“He’s gotta show that he’s a world statesman,” said Delury. “He’s gotta be able to message that back to North Korea to say, ‘This was a win for us — as a country, as a regime.'”

Susan Rice, who was National Security Adviser under former President Barack Obama and a U.S. ambassador to the United Nations, said others have made deals with North Korea only for the North to break them.

“It’s gonna take quite a while. This is a very complicated set of issues and success can’t be declared on the basis of a happy meeting,” she said on “Face The Nation”. “The problem is that, at every turn, the North Koreans would make commitments and then break them and we need to be mindful that is again what might happen.”

Some Democrats have also criticized the president for keeping them in the dark about preparations for the summit.

Koreans in the Tri-State Area are often reluctant to talk about the implications of the historic summit, but one man in Fort Lee, New Jersey was optimistic.

“It’s changing,” he said. “Changing I think is better, better than nothing.”

(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)