Shortly after the apparent setback was reported, President Trump tweeted the translation of a letter he had received from Mr Kim, in which the North Korean leader said: "I deeply appreciate the energetic and extraordinary efforts made by Your Excellency Mr President".
An agreement to return the remains of United States service members was touted by the Trump administration as one of the commitments secured during the president's historic summit with Kim on 12 June. The U.S. Embassy in Seoul said it had no immediate information.
Now, however, the mood in Pyongyang appears to be more conciliatory, with Kim keen for another meeting with Trump. About 100 wooden transport cases were sent to the DMZ in recent weeks to prepare for receiving USA troop remains. Although Pompeo called the meetings "productive", North Korea said the lack of emphasis on security guarantees was "regretful".
An estimated 30,000 USA soldiers died in the 1950-53 Korean war.
President Trump tweeted out the note, dated July 6, on Thursday. Roughly 5,300 U.S. troops presumed to have been killed in the Korean war are unaccounted for. A total of 7,697 personnel remain unaccounted for from the Korean War.
North Korea said Saturday it was seeking the "earliest start of the working-level talks" on the recovery of US remains.More news: Gazza's message for Southgate and his England squad
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President Trump met with North Korean Dictator 26 days ago.
Kim Jong Un put potatoes ahead of Mike Pompeo during a U.S. visit to agree denuclearisation details, state media has suggested.
The most contrarian nugget of Carlin's analysis was his assertion that the statement, and North Korean domestic media's coverage of the visit, suggests progress was made.
Earlier Thursday, a diplomatic source here said the US and North Korea were still in talks to set a date for working-level dialogue over the repatriation of remains of American troops.
But following the meeting, North Korea released a statement calling the meeting "regrettable" and accusing the USA of using "gangster-like" tactics to push it towards nuclear disarmament.
North Korea has imposed a testing moratorium, with the last missile test occurring on November 28, and it destroyed its main nuclear testing facility, although experts say those moves could be reversed.