Even as teams of advance staffers survey ornate hotel ballrooms in Singapore for the June 12 encounter, some of the President's advisers privately say the chances of the talks occurring grew slimmer after North Korea adopted a harsher tone toward the United States last week and raised questions about Kim's commitment to, and definition of, denuclearization. Could it turn into an embarrassment?
South Korea anxious about Kim's bellicose weapons testing and Trump's similarly bellicose warnings about a looming war, was instrumental in convincing the two Cold War foes to sit down and talk. But the president has reportedly spent the weekend agonizing over the decision. He said the worst-case scenario was canceling the meeting.
"We believe there is a 99.9 per cent chance that the North Korea-US summit will be held as scheduled", Chung Eui-yong told reporters on the aeroplane carrying Mr Moon to Washington.
Trump attempted to assuage Kim's concerns last week, promising "protections" should he abandon his nuclear weapons.
The exclusion, a sharp departure from the conciliatory mood between the Koreas since the South hosted the Olympics in February, deepens a standoff that began last week when Pyongyang signaled it would cut off all high-level talks with Seoul in response to the joint military exercises.
Neither Seoul nor Washington would comment on the details of the weekend conversation.
In the view of some analysts, such as Institute for Corean-American Studies Fellow Tara O, Moon appears anxious to persuade Trump to go ahead with the Kim summit and to get the USA president to grant sanctions relief so planned joint South-North projects would be able to proceed.
After weeks of flowery coverage of historic talks with South Korea and the United States, North Korea's media returned to its trademark angry tone on Tuesday, just as foreign journalists arrived in the country to cover the demolition of its nuclear test site.
According to documents obtained by the Mainichi Shimbun, each of the horizontal shafts is about 200 meters long, U-shaped and has 10 doors - allowing blast gases from the innermost compartment to be stopped by those doors.
Observers in South Korea say no one should be surprised by all the conflicting signals.
President Donald Trump will meet South Korean President Moon Jae-in as USA officials try to figure out whether Pyongyang is serious about negotiating a deal on denuclearisation.
And it could be a deciding factor in whether the Trump-Kim summit moves forward.
"I want this to happen, and North Korea to be VERY successful, but only after signing!" He's also a graduate of the University of Waterloo.
"For Moon, it's mission impossible", Kazianis said. That same day, Pyongyang also warned Mr. Kim might "reconsider" the USA summit over hard-line comments from Mr. Trump's new National Security Adviser, John Bolton. About 28,000 American forces are based in South Korea.
More recently, a commentary published by North Korea's state news agency in 2016 said that "history proves that powerful nuclear deterrence serves as the strongest treasure sword for frustrating outsiders' aggression".
That's a goal also set by previous US administrations that proved impossible to achieve and one that few observers in the South believe Pyongyang would consider now that its program is virtually complete. But Trump also suggested Kim risks being overthrown and possibly death if the arsenal remains. It was Moon's government that delivered the initial invitation from Kim for a meeting, and South Korea has been pushing the USA toward a peaceful resolution to the nuclear crisis.
Since March, Kim has also been warming up to Beijing.
How does Trump's recent withdrawal from the Iran nuclear deal impact his efforts with North Korea? Those sanctions continue for now, though Washington is anxious China has relaxed enforcement along the frontier between the two countries.
Indeed, the relationship between Beijing and Pyongyang seems much more amicable.
He suggested that while the administration has said it's content to continue the maximum pressure campaign should talks falter, Trump appears intent on making a deal.
This has been seen by North Korean leaders as a reason to hold onto their nuclear weapons to ensure regime survival.
Analysts saw North Korea's perceived slow peddling as evidence of what they feared all along, that Pyongyang may have been playing for time.
Beijing may share Pyongyang's goal of reducing the American military presence on the Korean Peninsula, but it hasn't been happy with Kim's nuclear ambitions. "If the USA and the South Korean authorities persist in the confrontation policy and war moves against the DPRK, oblivious of this fact, they will be held wholly accountable for all the ensuing consequences", it said.