"For now, we are not considering picking up the phone", the official said.
"We'll see what happens", Trump told reporters at the White House on Friday, adding that his administration was in talks with Pyongyang and the summit was still possible on its originally scheduled date of 12 June.
On Thursday morning, the White House released a letter Trump wrote to Kim saying: "I was very much looking forward to being there with you. We'd like to do it".
It's not clear whether South Korea, a close USA ally intimately involved in the negotiations with North Korea, was informed in advance that Trump was calling off the summit.
Kim Jong-un purportedly guiding the work for nuclear weaponisation.
USA officials also complained North Koreans did not show up to preparatory meetings and would not answer calls.
A further threat to cancel the summit comes on May 23 as North Korea calls US Vice President Mike Pence "stupid" after he warned Kim against trying "to play" Mr Trump.
"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.
The following month, Mr Trump threatens "fire and fury" if Pyongyang continues to threaten America, kicking off months of saber-rattling that set the world on edge.
Trump says: "Just the other day, Nancy Pelosi came out in favor of MS-13".
Nauert said the administration is wary of heading into a meeting without knowing that something concrete will come out of it. Nauert said she wasn't aware of whether the Trump administration is now in direct contact with Kim Jong Un's government. We're talking to them now.
National security experts were nonetheless left puzzled by the mixed messages coming out of the White House, which some argued would undermine talks.
Disrupted Body Clock Linked to Mood Disorders
People with lower relative amplitude were at greater risk of mental health problems such as depression and bipolar disorder . Daniel Smith , professor of psychiatry at the University of Glasgow and a leading author on the study.
"He wants to get something that's a long-lasting and an actual real solution".
In his letter, Trump responded in kind, referencing US nuclear capabilities "so massive and powerful that I pray to God they will never have to be used".
Narang, an author of two books on nuclear strategy, told VOA News that "one camp may prefer to see if working-level diplomacy can get things back on track, and maybe eventually get to a summit".
Trump's aides had warned that merely agreeing to the summit had provided Kim with long-sought global legitimacy and, if Trump ultimately backed out, risked fostering the perception that the president was insufficiently committed to diplomatic solutions to the nuclear question.
Mr Bolton provoked Pyongyang's ire by suggesting it followed Libya's lead on denuclearisation - evoking memories of the demise of the late Moamer Kadhafi who was killed in a 2011 uprising after agreeing to scrap his nuclear program in 2003.
Trump had initially sought to placate North Korea, saying he was not pursuing the "Libya model" and Sanders said he was following "the President Trump model".
At an economic forum in St. Petersburg, Chinese Vice President Wang Qishan said it was necessary to ensure security on the Korean peninsula, which touched on China's core interests.
UN Secretary General Antonio Guterres said the United States and North Korea should not give up, saying "nerves of steel" were required.
"At a time when the U.S".
Some analysts anxious that cancelling the summit could prompt a resumption in hostilities, including renewed shorter-range missile tests or stepped-up cyber attacks by Pyongyang and increased sanctions or deployment of new military assets by Washington.
The North Koreans were a no-show for a preparatory meeting in Singapore last week, part of a trail of broken promises, lack of good faith and poor communication prompting the president's decision, according to administration officials.
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