But the North's Kim Kye Gwan countered that Pyongyang's angry statements were "just a backlash in response to harsh words from the U.S. side that has been pushing for a unilateral denuclearisation". Worldwide journalists were present, but the USA government can't verify the site's destruction.
If the summit plans follows through, it would be the first time a sitting United States president and North Korean leader would meet. If the North makes any economic demands for the simple pleasure of a meeting-something it has done time and time again-then we will know that North Korea is simply trying to weaken the sanctions regime without making any concessions.
In a move the country said would "transparency of the discontinuance of nuclear test (s)", the DPRK said the site, previously used in all six of the North's nuclear tests, was now decommissioned.
She said Pompeo and Kang had reaffirmed their commitment to denuclearize the Korean Peninsula "and to the ironclad alliance" between the two amid concerns that Trump had not given Moon advance notice of his earlier decision to scrap the Kim summit.
South Korea also would continue efforts to improve ties with the North, the office of President Moon Jae-in said after Moon's top security advisers met for the second time on Friday.
In many respects, that could be the simplest of explanations as to why Kim Jong-un has offered, and President Trump has accepted, to meet to negotiate what could be the greatest diplomatic opening since Nixon went to China in 1972.
The president did not call South Korean President Moon Jae-in or Japanese Prime Minister Shinzo Abe to inform them of it, White House officials confirmed.
Washington has made it clear it wants to see the "complete, verifiable and irreversible denuclearization" of the North.
And given Trump's entertainment background, other experts said it would be wise not to attempt to divine the machinations of the mercurial president until the dust settles.
North Korea issued an unusually restrained and diplomatic response to Trump, saying it's still willing to sit for talks with the United States "at any time, (in) any format".
Analysts say Kim's diplomatic outreach in recent months after a flurry of nuclear and missile tests in 2017 indicates he is eager for sanctions relief to build his economy and the worldwide legitimacy the summit with Trump would provide.
Mr Trump added: "Everybody plays games".
A White House official quoted by Reuters news agency described the comments about Mr Pence as the "last straw".
"That diplomats are still at work on the summit, (the) possibility of a summit, so that's very good news", Mattis said. He added that his country's "objective and resolve to do our best for the sake of peace and stability of the Korean Peninsula and all humankind remain unchanged".
"It was a very nice statement they put out", Trump said as he left the White House to deliver a commencement address at the US Naval Academy.
He even said it was possible the meeting could take place on the originally planned June 12 date.
A senior administration official in the U.S. later gave further details, saying North Korea had shown "a profound lack of good faith".
Trump is tweeting that if the summit happens it "will likely remain in Singapore on the same date, June 12th., and, if necessary, will be extended beyond that date".
Ponsei University's John Delury, wrote: "So much of our frustration and failure derive from talking about North Korea rather than talking to North Koreans, treating talks as a reward".
Trump, who considers himself a master dealmaker, has confounded aides and allies at every turn of the fateful flirtation with the North.
Park tells TIME that although the young generation of South Koreans tended to be skeptical of improvements in inter-Korean relations, Moon and Kim's April 27 meeting had "inspired the young generation to see North Korea differently". Libya's leader Muammar Gaddafi was executed following a Nato-backed uprising less than eight years after surrendering his nascent weapons program.