Vietnam is feverishly preparing for the high-profile event, Trump's second visit to the country and the first for a North Korean leader since Kim's grandfather Kim Il Sung travelled to the communist country in 1964.
On Tuesday, the US State Department said sanctions on North Korea would be maintained until Washington achieved final results of full verified denuclearisation.
Thae, the former diplomat in London, said the unorthodox new breed of negotiators was aimed at driving a wedge between the free-wheeling Trump and his team of technocrats, who were mostly cautious and skeptical about North Korea's claims of pursuing denuclearization.
"I hope that very positive things are going to happen", he said.
The two leaders held their first meeting in Singapore previous year, after which the White House said in a statement that Kim "reaffirmed his firm and unwavering commitment to complete denuclearization of the Korean Peninsula".
Trump said he would like to see the ultimate denuclearization of the DPRK, but at the same time noted that he was "in no particular rush" given that the sanctions remain in effect and Pyongyang has refrained from nuclear and missile testing.
"I really want the two leaders, or just one of them, to come and see my works here".More news: Two hundred families trapped by Islamic State in Syria, UN says
He arrived from Beijing, where he spent a night en route from North Korea.
Speaking to reporters at the White House on Wednesday, Trump also said he expects to meet with Kim again after their February 27-28 summit in Hanoi, the Vietnamese capital.
Biegen and Kim Hyok Chol met in Pyongyang earlier this month to hammer out United States and North Korean positions on denuclearisation ahead of the much-anticipated meeting. A diplomatic source in Seoul said, "North Korea will aggressively demand an easing or lifting of sanctions until the day of the summit".
Kim's newly appointed nuclear negotiator, Kim Hyok Chol, arrived in Hanoi on Wednesday, a source with direct knowledge said.
A statement from South Korea's presidential office said Moon offered his country's assistance to President Trump as a "concession" to Pyongyang in order to expedite North Korea's denuclearization.
The two envoys met earlier this month in North Korea's capital to discuss details of the February 27-28 summit.
Vietnam Prime Minister Nguyen Xuan Phuc told the summit organising committee on Tuesday that security during the summit was top priority, Vietnam's government said on its website on Wednesday.