About an hour-and-half later, security and police roped off the lobby and ordered everyone in earshot to put their mobile phones away. Kim emerged from an elevator to leave for a meeting with Singapore's Prime Minister, Lee Hsien Loong.

He sauntered to the hotel front entrance in a relaxed gait, surrounded by bodyguards in identical haircuts and black suits.

North Korean leader had landed in Singapore ahead of a summit that could end a nuclear stand-off with the US and transform his impoverished country.

Kim arrived via an Air China 747 that had earlier touched down at Changi Airport.

He was greeted by Singapore's Foreign Minister, Vivian Balakrishnan, who posted a picture on Twitter of him shaking hands with Kim and the message: "Welcomed Chairman Kim Jong Un, who has just arrived in Singapore".

Trump arrived later Sunday evening and went straight to his hotel, the Shangri-La.

Authorities have beefed up security around the leaders' hotels in central Singapore.

The Trump-Kim summit, which will be held at the Capella Hotel on Tuesday morning, will mark the first time a North Korean leader has met a sitting US president.

Despite the initial high stakes of a summit meant to rid North Korea of its nuclear weapons, the talks have been portrayed by Trump in recent days more as a get-to-know-each-other meeting.

Trump has also raised the possibility of further summits.

Kim has shown surprising diplomatic skills in his meetings with overseas leaders this year.

He went out of his way to be cordial during two summits with South Korean President Moon Jae-in in April and May.

Ever since Trump shocked allies, White House officials and, by some accounts, the North Koreans themselves when he accepted Kim's March invitation for a meeting, the two leaders have lurched towards an uncertain encounter that could affect millions.

"It's unknown territory in the truest sense, but I really feel confident," Trump told reporters on Saturday. "I feel that Kim Jong-un wants to do something great for his people and he has that opportunity and he won't have that opportunity again."

Trump's engagement with Kim fulfills the North Korean ruling family's long-unrequited yearning for international legitimacy, itself a substantial concession after more than a generation of US efforts to isolate the country on the global stage.

"It's never been done before," Trump said. "And obviously, what has been done before hasn't worked."

A triumvirate of forces is bringing the meeting to fruition, said Scott Snyder, senior fellow for Korea Studies and director of the Program on US Korea Policy at the Council on Foreign Relations. He described the summit as "produced by Kim, directed by [South Korean President Moon], and inspired by Trump".

Each man has his motivations: hard-hitting sanctions and a desire for legitimacy brought Kim to the table. Moon's efforts to avert a potentially catastrophic US first strike pushed Trump and Kim to take a risk. And Trump is the first US president willing to sit-down with Kim with so few concessions, believing his self-professed negotiating prowess will guide him though uncharted diplomatic waters.

Loading

Raising expectations in advance of the meeting, Trump said the outcome would depend heavily on his own instincts. He said he would know "within the first minute" of meeting Kim whether the North Korean leader was serious about nuclear negotiations.

"I think I'll know pretty quickly whether or not, in my opinion, something positive will happen. And if I think it won't happen, I'm not going to waste my time. I don't want to waste his time," Trump said.

"This is a leader who really is an unknown personality," Trump added of Kim. "People don't know much about him. I think that he's going to surprise on the upside, very much on the upside."

White House aides described Trump in the days after receiving the initial Kim invitation as being obsessed by visions of winning the Nobel Peace Prize and of using the skills he laid out in his book  The Art of the Deal to put his mark on the global order.

Loading

In recent weeks, though, Trump's enthusiasm has been tempered somewhat by the challenge of deal-making with such an unpredictable opponent. And there are worries from the White House to East Asian allies that Trump's desire for an agreement will lead him to accept any deal - even if it's a bad one.

Trump is dangling before Kim visions of protection, economic investment and even a White House visit, in return for a commitment to abandon his nuclear weapons program.

Kim, US officials say, has agreed to put his stockpile of 50 or more weapons on the table for negotiation, but the two countries have offered differing visions of what that would entail.

Despite Kim's apparent eagerness for a summit with Trump, there are doubts that he would fully relinquish his nuclear arsenal, which he may see as the guarantor of his survival.

US defence and intelligence officials have assessed the North to be on the threshold of having the capability to strike anywhere in the continental US with a nuclear-tipped missile - a capacity that Trump and other US officials have said they would not tolerate.

Trump reiterated his promise on Saturday that the US "will watch over and we'll protect" Kim and his government in return for him giving up the nuclear program.

With his Singapore summit, Trump is looking temporarily to escape his flaring personal conflicts with key US allies over trade as well as domestic pressure such as  the swirling Russia probe. Acutely aware of his coverage in the media, Trump has enjoyed how the impending North Korea summit has overshadowed some of the more negative coverage of his tumultuous White House.

Still, Trump's team has not always been on the same page, with Secretary of State Mike Pompeo - who has been leading the administration's efforts - more supportive, while the hawkish National Security Adviser John Bolton has been more sceptical. Bolton has been far less visible in the planning process, after a comment he made about favouring the "Libya model" for denuclearisation enraged the North Koreans.

Libya gave up its nuclear program at an early stage only to see its long-time dictator overthrown and killed less than a decade later.

En route to Singapore, Trump left behind a trail of diplomatic wreckage as he exited the annual G7 summit in Quebec on Saturday, highlighting the extent to which he increasingly keeps his own counsel, eschewing the cautionary advice of aides and confident in his ability single-handedly to attempt to redraw the global order.

In Canada, he threatened long-time allies over trade practices at a defiant exit press conference before abruptly withdrawing his endorsement of the group's final joint statement and tweeting that host Prime Minister Justin Trudeau was "weak."

"His message from Quebec to Singapore is that he is going to meld the industrial democracies to his will - and bring back Russia," said Steve Bannon, Trump's former campaign and White House adviser.

Agencies