US Secretary of State Mike Pompeo said the preparatory talks were moving quite rapidly "and we anticipate that they will come to their logical conclusion even more quickly than we anticipated", reports Reuters.
Mr Trump lashed out at his allies as part of a demonstration of strength as he flew into Singapore, according to a senior White House adviser. After greeting each other - an image sure to be devoured around the world - the two leaders planned to sit for a one-on-one meeting that a USA official said could last up to two hours, with only translators joining them.
Dr. Barry Goodfield, who's profiled notorious dictators including Saddam Hussein, said failure is not an option for President Donald Trump and North Korea's Kim Jong Un during the historic summit on Tuesday.
Exuding confidence, Trump said he has done relatively little formal preparation.
It's a dramatic departure for Trump, who kicked off 2018 bragging that his nuclear button is "much bigger" than Kim's.
Asked how long it would take for him to work out if Kim was serious about striking some kind of peace deal, Trump replied: "I think within the first minute I'll know".
At issue is whether Kim would be willing to abandon a nuclear weapons program that has advanced rapidly in recent years, posing an increasing threat to the USA and its allies.
The sudden change in schedule added to a dizzying few days for foreign policy for Trump, who shocked USA allies over the weekend when he used a meeting of the Group of 7 industrialized economies in Canada to alienate America's closest friends in the West. Lashing out over trade practices, he lobbed insults at the G-7 host, Canadian Prime Minister Justin Trudeau. He credits his administration's "maximum pressure" campaign with getting Kim to the table.
Kim Yo Jong, believed to be 30 and one of the North Korean leader's closest confidants, reportedly arrived at Singapore's Changi Airport about an hour after the despot's Chinese charter plane touched down.
But Pompeo has refused to answer reporters' questions about whether the two governments had reached agreement on how to define denuclearization, and how it might play out.
"North Korea has previously confirmed to us its willingness to denuclearise and we are eager to see if those words prove honest", he said.
Cho Sung-kwon, a 62-year-old pensioner, added: "It would be a good thing if we stop fighting".
Trump hopes the landmark talks will kick-start a process that eventually see Kim give up his nuclear weapons in an irreversible manner that can be verified internationally.
The president has said that he would be willing to guarantee the safety of Kim's regime - though it's not clear how he would back that up.
Mr. Trump's top economic adviser, Lawrence Kudlow, said Mr. Trudeau's press conference had been a "betrayal" because Mr. Trump couldn't afford to show any weakness before his meeting with North Korea.
Unlike most other publications, USA Today had a different outlook of the Trump-Kim meeting. "Kim wants recognition for North Korea as a country, recognition for his family's right to rule it as a personal fiefdom and, ultimately, recognition of North Korea's status as a nuclear-armed power", the newspaper writes. A large limousine with a North Korean flag was surrounded by other black vehicles with tinted window as it sped through the city's streets.
Al Jazeera's Adrian Brown reports from Singapore.