Its outcome could prove pivotal in determining whether the two nations pursue a lasting peace or a fresh military conflict.
But the veteran diplomat, who was briefly considered for a post as Trump's ambassador to South Korea, warns the administration will face the same challenges and trade-offs in North Korea that its predecessors did.
Besides, Singapore's prime minister "wished Chairman Kim success for the US-DPRK Summit and expressed hope that the US-DPRK meeting will advance the prospects for peace and stability on the Korean Peninsula and the larger region".
The top U.S. and North Korean negotiators had earlier emerged from a last-ditch meeting at the Ritz Carlton with pursed lips, and no sign of whether an attempt to narrow the gap between United States and North Korean expectations of what denuclearisation should look like, had worked. Would conventional politics have even taken us this far?
"It's not like the Trump-Kim summit will solve everything", he added.
Responding to a reporter's question on the subject, the secretary of state added that the U.S.is "prepared to take actions that will provide [North Korea] sufficient certainty that they can be comfortable that denuclearization isn't something that ends badly for them". It's a Short List.
The G7 jolt comes as an unprecedented meeting between Trump and North Korea's Kim is scheduled for June 12 in Singapore, with investors also braced for a raft of other key events.
He has made two trips to China since March to meet President Xi Jinping, and held summit talks with South Korean President Moon Jae-in in April and May in the Demilitarized Zone, which separates the two Koreas.
The White House says Trump will address the media on Tuesday following his summit with Kim and depart Singapore at approximately 8 P.M. The president had been expected to leave Singapore on Wednesday morning.
"We will not be surprised by any scenario", said the official.
"As the venue and time of the summit have already been announced, security for Kim Jong Un will be tighter than for any other VIPs", said the professor, who was the first academic to establish a university major in South Korea on guarding and protection.
Kim Jong Un enjoys night-time stroll in Singapore ahead of historic summit
Kim has been more cryptic and calculating, with his regime vacillating between welcoming talks with the USA, ignoring American overtures, and sharply attacking some of Trump's top officials with insults and threats, said Patrick Cronin, director of the Center for a New America Security's Asia-Pacific security program.
In a sign of lingering tensions, the North Koreans have been closely scrutinizing all American staffers who are slated to be in any U.S. Past nuclear deals have crumbled over North Korea's reluctance to open its doors to outsiders.
Kim's summit with Trump has captured intense global attention after a turn to diplomacy in recent months after serious fears of war past year amid North Korean nuclear and missile tests. It will be the first time a sitting US president has met with a North Korean leader.
Singapore's foreign minster Vivian Balakrishnan tweeted a selfie of himself with Mr Kim during the surprise walkabout.
"I also think I'll know whether or not it will happen fast.it may not".
President Trump is expected to use the meeting to pressure Pyongyang into giving up its nuclear weapons in return for relief from economic sanctions.
The president has said that he would be willing to guarantee the safety of Kim's regime - though it's not clear how he would back that up.
But while Kim has made some gestures in that direction - suspending nuclear and missile tests and making a show of disabling a nuclear test facility - veteran diplomats are skeptical that North Korea will surrender its nuclear weapons altogether. The North Korean autocrat's every move will be followed by 3,000 journalists up until he shakes hands with Trump.
The leaders of the United States and North Korea are gearing up for their historic first meeting which, if successful, could put to rest longtime fears of a war on the divided Korean Peninsula. "We've seen how many inadequate agreements have been struck in the past".
"You know the way they say you know if you like somebody in the first five seconds?"
"No matter what happens, President Trump and Kim Jong Un are going to call it a success", said former Central Intelligence Agency analyst Sue Mi Terry, who's now a senior fellow at the Center for Strategic and International Studies. "It's about attitude, it's about willingness to get things done".