Trump to meet 1-on-1 with Kim Jong Un: US official Trump spent a day in Singapore ahead of his historic meeting with Kim Jong Un.

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President Donald Trump and North Korean leader Kim Jong Un's historic meeting will begin with a one-on-one encounter, a White House official confirmed to reporters in Singapore Monday.

The official declined to say how long the first meeting is expected to last, but said it will take place prior to an expanded meeting where U.S. and North Korean officials would be in attendance.

Diplomats and foreign policy experts have criticized the idea of a U.S. president sitting down solo with the North Korean dictator, saying it heightens the potential for a misleading readout from Kim that could come into conflict with Trump's account of the exchange.

Secretary of State Pompeo briefed reporters in Singapore Monday evening, painting an optimistic picture of progress achieved between the U.S. and North Korean delegations leading up to Tuesday's summit.

"The talks continue this afternoon even as we sit here now," Pompeo said. "They're in fact moving quite rapidly and we anticipate they will come to logical conclusion even more quickly than we had anticipated."

Pompeo also sought to dismiss media reports that the U.S. currently lacks the necessary expertise to coordinate the full dismantling of North Korea's nuclear program.

With less than 24 hours until his historic face-to-face encounter with Kim, Trump spent his Monday in Singapore fuming on Twitter over his weekend trade spat with G-7 allies and paying a visit to Singapore's prime minister.

The president kicked off his first full day in Singapore with a tweet acknowledging the "excitement in the air" surrounding the summit.

But that message was just one in a series of five other tweets that doubled down on the president's escalating trade feud with Canada and European allies who were in attendance at the G-7 summit over the weekend.

The president's tweets followed Sunday show appearances by his top economic aides Sunday who assailed Canadian Prime Minister Justin Trudeau for comments he made in a press conference following the president's early departure from the G-7 summit.

"I have made it very clear to the president that it is not something we relish doing," Trudeau said, speaking of his decision to implement retaliatory tariffs against the U.S. "But it is something that we absolutely will do because Canadians, we're polite, we're reasonable, but we also will not be pushed around."

Despite the comments being largely a repeat of previously expressed concerns by Trudeau, they earned a furious rebuke from both the president and his advisors, who quickly pulled the U.S. away from endorsing a joint statement released by rest of the G-7 allies.

Director of the National Economic Council Larry Kudlow went as far as to suggest Trudeau was attempting to specifically undermine Trump and damage his negotiating position ahead of his summit with Kim.

"He is not going to allow other people to suddenly take potshots at him hours before that summit," Kudlow said on CBS' Face the Nation. "And, number two, Trudeau should have known better."

White House trade adviser Peter Navarro took it even further, saying, "there's a special place in hell for any foreign leader that engages in bad faith diplomacy with President Donald J. Trump and then tries to stab him in the back on the way out the door."

The rhetoric earned stiff rebukes from other G-7 attendees.

"International co-operation cannot be dictated by fits of anger and throwaway remarks," a spokesperson from France's Elysee Palace said Sunday.

President of the European Council Donald Tusk tweeted, "There is a special place in heaven for Justin Trudeau."

The feud threatened to overshadow one of the most highly anticipated diplomatic meetings in recent memory, as the president spent his first full day in Singapore with a relatively light public schedule.

The president first visited Istana Palace for a meeting with Singapore Prime Minister Lee Hsien Loong, who he thanked in brief remarks for being able to host the major summit.

“We appreciate your hospitality and professionalism and friendship,” Trump said, seated at a long banquet table ahead of a working lunch with delegations from the U.S. and Singapore.

Trump called the prime minister a friend and said “this was a choice that we made very consciously.”

He teased forward to Tuesday’s "very interesting” meeting and predicted a good outcome.

“We’ve got a very interesting meeting in particular tomorrow. I think things could work out very nicely,” he said.

Following the lunch, Singapore's Minister for Foreign Affairs Vivian Balakrishnan tweeted out a picture showing the president was gifted with a birthday cake. Trump will celebrate his 72nd birthday on Thursday.