Foreign Minister Kang Kyung-wha says South Korea will make sure if the summit does take place, "it's a meaningful meeting with good outcome". "However, I would strongly urge the administration to remember that Kim Jong Un, like his father and grandfather before him, have long sought a visit from the President of the United States to enhance their own prestige and justify their unsafe pursuit of nuclear weapons".
But the alarm bells have been ringing even louder since last July when Pyongyang conducted two intercontinental ballistic missile tests, declaring that the entire United States was now within its range.
News of the summit, which South Korean President Moon Jae-in said was "like a miracle", is the latest step in a quickening detente.
During their meeting at the White House, Chung reportedly told Trump that Kim expressed optimism for US-North Korea dialogue, saying he hoped it would be held "as early as possible".
August 9: Trump says North Korea had best not make more threats or "they will be met with fire and fury like the world has never seen". "Trump is dismembering the State Department".
They say it all depends on how US officials manage the process and figure out what exact concessions they are going to receive in what sort of document and with what kind of follow-up.
He told Sky News that President Trump should not go ahead with the meeting without clear commitments.
Except that the original agreement, as outlined by the South Koreans, was only that Kim would halt nuclear and missile tests while talks were underway.
The North Koreans "are coming to the table despite the United States making zero concessions and, in close coordination with our allies, we have consistently increased the pressure on the Kim regime".More news: UK rolls out red carpet for Saudi crown prince amid protests
"Trump blusters that if sanctions do not work, the US should go over to rough phase II and that as it is a very rough action, it would make the whole world unhappy", the newspaper noted.
The president had done what presidents from Eisenhower forward have tried - opened a relationship with the most isolated and perhaps unsafe country on earth, got the North Koreans to talk of denuclearization and even to acknowledge the need for the annual joint U.S. -South Korea military drills "must continue".
All of this would be so that "when the two principals met, there was some kind of understanding of what they were going to talk about, what potential agreement they would reach, and a lot of it would be relatively well scripted", says Jay Lefkowitz, who served as President George W. Bush's Special Envoy on Human Rights in North Korea.
The announcement triggered a rise in global stock markets while world leaders voiced hope that the summit would deflate tensions that had been building dramatically in recent months. Neutral Switzerland, which often hosts summits, said it was ready to facilitate the meeting.
Tillerson's comments follow a sudden announcement that Kim had to meet with U.S. President Donald Trump in person "as soon as possible".
USA -based experts say North Korea appeared to show last November that it has succeeded in developing a missile capable of delivering a nuclear weapon anywhere in the United States. That job is complicated by the fact that the USA public has been told for many years that you can't negotiate with North Korea-despite the fact that the United States negotiating team in the late 2000 believed they were close to agreements to solve both the nuclear and missile problems.
Trump's positive outlook on relations with Kim Jong Un is a marked departure from social media taunts in November of a year ago, in which he called Kim "Little Rocket Man" and noted that his people and military "put up with living in such terrible conditions".
"If Trump goes at all, and expects to announce a denuclearized North Korea, he will leave disappointed and maybe angry enough to believe that talks are useless and only military options are left", Narang warned.
November 29: North Korea's third ICBM test demonstrates a potential range that could reach Washington, D.C.
During the call, Mr Trump also referred to Mr Kim as a "madman with nuclear weapons" who could not be let to run loose.