Mr. Trump reiterated Friday night that the U.S.is having "very productive talks with North Korea" and the summit could still take place June 12th.
The president's comments on Twitter came barely 24 hours after he wrote to North Korean leader Kim Jong-un to cancel the disarmament talks, saying Pyongyang had been showing too much "hostility" toward the U.S.
"The two leaders frankly exchanged their opinions on implementing the April 27 Panmunjom Declaration [which the two struck in April at their first historic summit] and for the successful staging of a U.S. -NK summit", Blue House spokesman Yoon Young-chan said.
Summit meetings of this kind usually involve months of detailed planning and some analysts have expressed disquiet that private discussion of policy differences appears to have been replaced by "diplomacy by tweet", our correspondent adds. The person, who asked not to be identified discussing internal matters, said the "maximum pressure" campaign to strangle North Korea's economy is working, and Kim's regime will have to come to the table eventually.
The summit would be an unprecedented meeting between a sitting U.S. president and a North Korean leader, which Washington hopes will result in the full denuclearization of the reclusive state. Moon will brief the media on the unexpected meeting at 10 a.m. Sunday, his office said.
Trump scrapped the meeting in a letter to Kim on Thursday after repeated threats by North Korea to pull out over what it saw as confrontational remarks by USA officials demanding unilateral disarmament.More news: Census: Chicago's population drops 3rd year in a row
Trump eventually pulled the plug on talks in a personal letter to Kim on Thursday.
President Moon Jae-in had earlier said he was "very perplexed" and that it was "very regrettable" that the summit was not going ahead.
But he left the door open to future meetings and Pyongyang's immediate reaction was to say it was willing to sit down "at any time", prompting Trump to reply that the Singapore summit could still take place.
Trump, in his letter to Kim, objected specifically to a statement from a top North Korean Foreign Ministry official.
"It was a very nice statement they put out", Trump told reporters at the White House.More news: Hawaii's Kilauea Volcano Threatens Crucial Israeli-Owned Power Plant
Elms explains that "the use of the term "Libya" and repeated discussions about unilateral disarmament are very hard kind of language to use before you've even had the opportunity to sit down and meet for the first time".
"We even inwardly hoped that what is called "Trump formula" would help clear both sides of their worries and comply with the requirements of our side and would be a wise way of substantial effect for settling the issue", he said. They did what they could to get the Koreans to agree to go to the summit.
Trump's latest about-face sent officials scrambling in Washington. The presidential Blue House did not immediately provide more details.
It also was unhappy about the North's failure to allow global observers to verify the dismantling of the Punggye-ri test site, the staging ground for all six of its nuclear tests.
"He wants to get something that's a long-lasting and an actual real solution".More news: Shahid Khaqan Abbasi clarifies Nawaz Sharif's 26/11 remark