Mr Trump tweeted the venue on Friday in Washington, saying Mr Biegun had just left North Korea after a "productive meeting" on the summit. "I look forward to seeing Chairman Kim & advancing the cause of peace!" he added.
"Our discussions were productive", Biegun said after the three-day meeting in the North Korean capital.
It also confirmed Biegun had agreed to meet his North Korean counterpart Kim Hyok Chol again before the summit.
Casting doubt on North Korea's willingness to dismantle its nuclear arsenal and possibly throwing a wrench into talks in Vietnam is a confidential report from the United Nations which claims the communist state is still developing its nuclear and ballistic missiles.
Since their historic face-to-face meeting in Singapore eight months ago, North Korea has made little progress toward giving up its nuclear weapons and continues to do what it can to evade sanctions.
South Korea's government couldn't immediately confirm the report.
He also said Kim Jong-un had previously committed to "the dismantlement and destruction" of all North Korea's plutonium and uranium facilities, which provide the material for nuclear weapons.
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U.S Secretary of State Mike Pompeo hailed Vietnam's success story during his visit previous year, adding that North Korea can learn from Hanoi.
Biegun will hold another round of working-level talks with North Korean officials "in a third Asian country" other than the two Koreas next week, spokesman Kim continued.
These developments have given rise to concerns that the two leaders could settle for the disposal of North Korea's intercontinental ballistic missiles (ICBMs), which the USA regards as a direct threat to its national security.
"North Korea, under the leadership of Kim Jong Un, will become a great Economic Powerhouse", he wrote.
On Wednesday, Stephen Biegun, U.S. special representative for North Korea, arrived in Pyongyang for talks about the envisioned summit.
At their landmark summit in Singapore past year, the mercurial U.S. and North Korean leaders produced a vaguely worded document in which Mr Kim pledged to work towards "the denuclearisation of the Korean peninsula". In a speech last week, the U.S.'s envoy to North Korea, Stephen Biegun, pointed to North Korea's "preliminary steps" to dismantle two test sites, Tongchang-ri and Punggye-ri, even though those efforts took place without global inspectors in place.
In a report earlier this week, it said actions including the illegal transfer of banned goods at sea could make sanctions - the worldwide community's main way of putting pressure on North Korea - "ineffective".
Biegun explained the outcome of his Pyongyang visit to Kang, ROK's foreign ministry said in a statement without elaborating further.