According to a senior administration official, other factors also led the president to cancel the summit, including poor communication, broken promises and the North Koreans' failure to show up for a preparatory meeting in Singapore.
Trump's announcement came a day after Pyongyang hardened its rhetoric, calling comments by Vice President Mike Pence "ignorant and stupid".
"Democrats are so obviously rooting against us in our negotiations with North Korea".
On the face of it, the events leading up to the cancellation were predictable. First Vice-Foreign Minister Kim Kye Gwan called Mr Trump's decision "unexpected" and "regrettable".
Some analysts see signs of a classic Trump manoeuvre to twist the process to his advantage.
Major Garrett, chief White House correspondent for CBS News. Sitting down as an equal with the USA president would go a long way toward legitimizing his regime on the world stage and weakening the rationale for continued trade sanctions, particularly by neighbouring China. But there is also no question that his abrupt decisions-first raising expectations, by so readily and eagerly embracing the prospect of a summit, and then dashing them, with his unexpected withdrawal-do not fit very well into the ponderous, incremental world of worldwide diplomacy.
"A summit between the leaders of the USA and North Korea would play a key role in denuclearisation".
Arguably, trying to interpret the United States president's moves in diplomatic terms is a mistake.
TRADE DEAL UNCERTAINTY Meanwhile, Trump also cast uncertainty over progress in trade talks, saying Wednesday that Washington would seek a new "structure" for the deal and a new direction for talks with Beijing, days after the two had taken conciliatory stances.
So are we back to square one?
The Chinese foreign ministry has urged the United States and North Korea to be patient and show goodwill, saying Beijing still wants the summit to go ahead. "You talk about your nuclear capabilities, but ours are so massive and powerful that I pray to God they will never have to be used", Trump wrote.
"I don't think Trump is doing the right thing if he wants to win the Nobel Peace Prize".
North Korea's response moved to place the blame for the failed meeting on the US.
President Moon invested much political capital and personal energy into brokering talks between Mr Trump and Kim Jong-un, but is now facing growing scrutiny over whether he oversold Pyongyang's willingness to give up its nuclear weapons.
In a letter to North Korea leader Kim Jong Un, Trump had blamed "tremendous anger and open hostility" by Pyongyang, but held out hope that the meeting could happen. "But we shouldn't spend all our time thinking about the deal, without focusing on here's what this needs to look like in order to what president has said, to keep Americans safe from the threat that North Korea presents today", Pompeo added.
In the city's Gwanghwamun Square Friday, a group of about 30 protesters holding the banners of South Korea's left-wing Minjung party had gathered to demonstrate against the cancellation of summit.
It was unclear whether Trump was engaged in what he saw as a negotiating ploy or if his moves were a manifestation of mounting internal concerns over ensuring a successful outcome for the summit.
Trump seemed pleased by the conciliatory tone of a North Korean statement issued after the summit was canceled Thursday, saying it was "willing to give the USA time and opportunities" to reconsider talks "at any time at any format", according to the Associated Press.
When asked if the summit could still be on June 12, Mattis was non-committal, saying only, "The diplomats are working it but nothing's changed".
How have other countries in the region reacted?
South Korea has been left reeling from the USA president's announcement.
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