Kelly and Mattis, both former Marine generals, warned Trump that the plan, if implemented, would alienate South Korea, ruin the Olympics and possibly trigger a hostile response from North Korea.
Trump sent a letter Thursday canceling the denuclearization talks after North Korean officials insulted Vice President Mike Pence's intelligence and reportedly became unresponsive to the summit planning process. "We'll see what happens". "We're talking to them now, it was a very nice statement they put out, we'll see what happens", Trump said. "They very much want to do it, we'd like to do it". "We'd like to do it".
He also added that North Korea remained open to resolving issues with Washington "regardless of ways, at any time, any format".
Moon said he was "perplexed" at Trump's announcement that he was canceling the summit because of what the USA president said was North Korea's "tremendous anger and open hostility".
It followed an announcement earlier in the day from the White House that Trump had cancelled the June 12 summit due to "open hostility" from Kim Jong Un.
The statement by Vice Foreign Minister Kim Kye Gwan, a longtime nuclear negotiator and senior diplomat, which said the North is "willing to give the USA time and opportunities" to reconsider talks that had been set for June 12 in Singapore, could be driven by a need to use the summit to ease crushing global sanctions, or by a determination that a summit with the mercurial Trump is the best opportunity the North will ever have to elevate itself, and its nuclear program, to equality with its archrival.
Just before Trump announced the cancellation of the meeting, North Korea declared it had "completely" dismantled its nuclear test site in the country's far northeast, in a carefully choreographed goodwill gesture ahead of the summit. The statement was issued in response to Trump's abrupt cancellation of the June summit between the two countries in the US bid to get North Korea to abandon its nuclear weapon.
Meanwhile, South Koreans said they had not been informed about the U.S. decision to pull, with Seoul officials having said just days earlier that there was a "99.9%" chance of the meeting going ahead as planned.
In recent months, Trump had traded his bellicose threats of "fire and fury" for bouquets of flattery, calling Kim "very honorable" and exuding confidence that he could seal a deal that had eluded his predecessors for generations. "If North Korea is serious, then we look forward hearing from them at the highest levels".
White House spokeswoman Sarah Sanders told reporters Trump did not want a meeting that was "just a political stunt".
"He wants to get something that's a long-lasting and an actual real solution". We're talking to them now.
Malema slams African governments for attending Jerusalem embassy opening
Speaking to Al-Jazeera on Wednesday, Hamas's Gaza head Yahya Sinwar warned his movement could return to armed resistance. Israel regards all of the city, including the eastern sector it annexed after the 1967 conflict, as its capital.
"If the meeting takes place on June 12, we'll be ready, if it takes place on July 12, we will be ready".
Trump's initial overture to Kim, made with little input from his top foreign-policy advisers, was typical of a president who has flouted convention from the moment he took office.
The White House has repeatedly offered mixed messages.
North Korea had sharply criticized suggestions by Trump's national security adviser, John Bolton, and Vice President Mike Pence that it could share the fate of Libya if it did not swiftly surrender its nuclear arsenal. Libyan leader Muammar Gaddafi was deposed and killed by NATO-backed militants after halting his nascent nuclear program.
USA regional allies Japan and South Korea, as well as North Korea's main ally, China, urged the two countries to salvage the summit on Friday.
"It's not "if" he ends the North Korean program, it's 'how and when, '" Graham said.
Japanese Prime Minister Shinzo Abe, at the same forum, regretted the cancellation and said the world should keep doing its bit to make the summit happen.
Trump attacked House Democratic Leader Nancy Pelosi over her criticism of his decision to publicly brand MS-13 gang members "animals" during a White House meeting on immigration last week. But late a year ago, Trump accepted an invitation to speak with Kim.
Many observers had expected a belligerent North Korean response to Trump's cancellation, but the comments by Kim, the North's vice foreign minister, seemed, at times, nearly meek, and in stark contrast to the bellicose declarations past year of the North's willingness to pursue nuclear war.
But he said talks could still go ahead "at a later date".