At the June 12 Singapore summit, U.S. President Donald Trump and North Korean leader Kim Jong-un committed to recovering the remains of fallen American troops, including the immediate repatriation of those already identified.
Earlier Thursday, a diplomatic source here said the USA and North Korea were still in talks to set a date for working-level dialogue over the repatriation of remains of American troops. "Great progress being made!"
North Korean officials did not turn up to a Thursday meeting with the US military about repatriating the remains of American war dead, according to a USA official with knowledge of the situation.
Kim expresses "invariable trust and confidence" in the president and wishes that "epochal progress" in promoting relations will "bring our next meeting forward".
"I deeply appreciate the energetic and extraordinary efforts made by Your Excellency Mr. President for the improvement of relations between the two countries", the letter read, in part.
The letter was dated just one day before North Korea accused the US of "gangster-like" demands following a visit and talks by Secretary of State Mike Pompeo.
"We will be ready", Mr Nauert said.
Trump met with Kim in Singapore on June 12-the first meeting between leaders of the two countries.
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North Korea proposed to reschedule the meeting for Sunday.
North Korean officials denounced the meeting at its conclusion, accusing the US of having a "gangster-like" attitude in negotiations.
Last week, North Korea accused the USA of using a "gangster-like" tactics to push it towards nuclear disarmament after a fresh round of high-level talks. Kim also agreed then to repatriate remains of US troops who died during the Korean War six decades ago. Add North Korea as an interest to stay up to date on the latest North Korea news, video, and analysis from ABC News.
The Americans called North Korean representatives and scheduled a generals' meeting between the two nations to take place Sunday.
Trump himself has remained upbeat about the outcome of the first summit between the leaders of the USA and North Korea.
The US later said that North Korea had offered to meet on 15 July.
The letter contrasts with a statement put out on July 7 by an unnamed North Korean official saying that Washington's attitude and stance were "regrettable" and that the United States "came up only with its unilateral and gangster-like demand for denuclearization".