The Washington Post first reported the team, which also included Allison Hooker, the Korea expert on the White House National Security Council, met with Choe Son Hui, the North Korean vice foreign minister.
"Trump said preparation meetings are going on "as we speak in a certain location which I won't name", like the location, it's not very far from here". "It will happen!" Mr. Trump tweeted Sunday afternoon.
Before cancelling the summit last week, Mr Trump said that China had eased up enforcement of sanctions on its border.
AP reported he was heading to Washington, DC, but changed his flight to New York City. Trump and Abe "affirmed the shared imperative of achieving the complete and permanent dismantlement of North Korea's nuclear, chemical, and biological weapons and ballistic missile programs", the White House said in a statement.
North Korea has "brilliant potential" and will be a "great economic and financial Nation one day", Donald Trump says.
Meetings between American and North Korean officials are under way simultaneously in the truce village of Panmunjom, on the North and South Korean border, and in Singapore.
The Washington Post reported that senior diplomat Sung Kim was leading the us delegation, and that the two sides planned to continue talking Monday and Tuesday. We're looking at June 12 in Singapore. Trump told reporters that they are still considering Singapore as the venue for their talks.
On Monday morning, Trump discussed the summit with Japanese Prime Minister Shinzo Abe, who has encouraged maintaining firm pressure on North Korea until agreements over its nuclear and missile programs can be reached.
The general has always been a right hand man to North Korea's leader, playing a front-seat role during recent rounds of diplomacy aimed at ending the nuclear stalemate on the Korean peninsula.
"Chairman Kim agreed on that", he added.
It wasn't immediately clear whether the American officials including Sung Kim, the USA ambassador to Manila, were heading Tuesday to the border village between the Koreas where they met with North Korean officials on Sunday.
It has long said it is open to eventually giving up its nuclear arsenal if the United States withdraws its troops from South Korea and ends its "nuclear umbrella" alliance with Seoul.
Sung Kim had been on standby in Seoul since last week.
"Even though they share the same resolve, there need to be discussions regarding the roadmap for how to make it happen, and that process could be tough", Mr Moon said, declining to define "complete denuclearisation".
CNN's Brooke Baldwin began by asking Ford why Trump got "outplayed" by North Korea. Roy Blunt, Missouri Republican, on "Fox News Sunday". "He knows what he can concede and what it means and what he cannot concede". They allowed Moon to push for a US-North Korean summit that he sees as the best way to ease animosity that had some fearing a war in 2017. "And I think unfortunately, the answer is no".
Moon later announced that Kim had reaffirmed his commitment to denuclearization and willingness to meet with Trump.
"Ultimately, I remain convinced that he does not want to denuclearize - in fact, he will not denuclearize".
Moon said North Korea was not convinced it could trust security guarantees from the United States. "And I'm hopeful that we'll work together to make sure that this summit is a success".
The summit is expected to take place in Singapore on June 12.
Those details were supposed to have been worked out two weeks ago, when Hagin traveled to Singapore to arrange details of the talks, but the North Korean delegation never arrived.