"I think that he's going to surprise on the upside, very much on the upside, we'll see", said Trump.
Before hastily setting off on Air Force One early from the Quebec resort summit for Tuesday's sit-down in Singapore with North Korea's Kim Jong Un, Trump spoke to a gaggle of reporters claiming the annual G-7 gathering could be reduced to "G-6 plus one". a clear knock at its neighbor Canada.
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In addition to protection, the North Korean delegation may fine-tune its security detail to project a particular image for Kim Jong Un, said Ahn Chan-il, a defector and current president of the World Institute for North Korea Studies.
"I think within the first minute, I'll know", Trump said, prompting a reporter to question how he would know.
Kim Jong Un embraces South Korean President Moon Jae-in, right, after their meeting at the northern side of the Panmunjom in North Korea on May 26.
"I personally don't believe in further shutting out North Korea from the rest of the world, and feel cultural exchange and dialogue - even through something as basic as tourism - is extremely important in better understanding each other", he said.
"You know the way they say you know if you like somebody in the first five seconds?" he added.
Trump repeated his warning the meeting in Singapore on Tuesday could prove to be very short, saying "I think within the first minute, I'll know" if Kim is serious.
"I think it would be an asset to have Russian Federation back in, it would be good for the world".
Donald Trump said North Korea has been working well with them ahead of the summit. He also suggested South Korea, China and Japan would be prepared to help the North's economy.
"For people like my father, they could go back to their homeland to their birthplace and revisit the country, so positive things like that will happen".
A Chinese private jet that discreetly landed in North Korea has departed Sunday en route to Singapore about an hour after its arrival in the communist state, a flight route-tracking website showed. "People don't know much about him. It really amazed me and I thought we can learn a lot".
During a promotional event, dubbed the "real" Trump-Kim summit, the men waved at shoppers as they walked through the crowded Bugis Junction mall.
Speaking in a series of Friday interviews with journalists from Asian countries that lie in close proximity to North Korea, Pompeo said that would include any possible clandestine sites unknown to those outside North Korea.
"So far so good", Trump said.
A half-mile away at the Shangri-La Hotel, where the US side will stay, Secret Service agents, in a casual uniform of khaki slacks and dark polo shirts, milled about the lobby.
Still, it's a serious contrast to the days past year when choice insults - Trump's "little rocket man" and Kim's "dotard" - were flying between Washington and Pyongyang during the North's nuclear and missile tests.
Trump delivered off-script comments as he was leaving a G-7 summit in Canada, a meeting at which he was at odds with US allies on issues such as trade.