National security advisers are briefing Trump daily about the summit, which he wants to use as a vehicle to persuade Kim to shut down North Korea's nuclear weapons program.
"We are in a materially different place than where we were a year ago, or even six months ago ... tensions are materially down", Joseph Yun, a senior adviser at the federally funded think tank U.S. Institute for Peace, testified before a Senate Foreign Relations subcommittee hearing.
He warned North Korea that only when they agree to complete denuclearization can they expect economic sanctions to lift.
Ahead of the summit, North Korea has been engaged in a flurry of diplomatic activity.
The Trump administration, she said, is actively preparing for the summit between the US President and the North Korean leader. The Shangri-La hotel had always been seen as the likely venue for the summit and had previously hosted former USA presidents George H.W. Bush and Barack Obama.
Kim Chang Son, the de facto chief of staff for the North Korean government, was seen at The Fullerton five-star hotel in Singapore last week during a visit to meet U.S. officials to work out the logistics for the summit.
The summit will be the first meeting between a serving US president and a North Korean leader.
"Because of the unique sensitivities and peculiarities of the summit, nearly anything unpredictable could possibly affect the summit itself", Graham Ong-Webb, a research fellow, at the S. Rajaratnam School of International Studies in Singapore, said.More news: Trump Blames FBI for Not Warning Him About Paul Manafort
Japan, which relied on the USA for its post-World War II diplomacy and security, has been absent in the recent burst of engagement with North Korea.
Trump also said he wanted to drop the term "maximum pressure" that his administration - and Japan - had used to describe an approach that combined tough economic sanctions with diplomacy and military threats from the U.S. president.
U.S. officials have welcomed Kim's recent announcement of a suspension of long-range missile tests and the closing of his nuclear bomb test site but say these steps are reversible.
He said as North Korea was being more co-operative he would hold off on imposing new sanctions.
"The president, the vice president and the secretary of state have all told me separately that their intent is to put together a treaty that will be submitted to the United States Senate under the constitution for certification", Sen.
Japanese officials declined to speculate on whether trade would join North Korea on the agenda at Thursday's talks, but White House spokeswoman Sarah Sanders told reporters that "trade issues and other matters" were expected to come up.
Pompeo has taken the lead on the North Korea negotiations and has twice met with North Korean leader Kim Jong Un.