The development is likely to fuel growing skepticism over North Korea's commitment to a complete denuclearization of the Korean peninsula as promised during last month's meeting between President Donald Trump and Kim Jong Un in Singapore.
Trump described the letter as a "very nice note" and said, "Great progress being made!".
Media reports following US Secretary of State Mike Pompeo's visit to Pyongyang last week painted a dire picture of denuclearization talks, seizing on a statement released by North Korea's Foreign Ministry decrying the Trump administration's "gangster-like" approach. Trump tweeted on Thursday alongside a copy of the letter, dated July 6.
North Korean leader Kim Jong Un has ordered his aides to "re-explain" to Tokyo the findings of a probe into the whereabouts of missing Japanese nationals suspected to have been abducted by Pyongyang decades ago, according to a South Korean activist.
The Pentagon says Pyongyang has indicated several times they have as many as 200 sets of remains that could be those of United States soldiers who died in the war.
And even as Trump released Kim's note, the U.S. was asking the UN Security Council to punish North Korea after finding that Pyongyang had violated restrictions on refined oil imports.
The UNC told the USA defense ministry about North Korea's proposal and is waiting for Washington's answer, the source added. "Great progress being made".
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The crash happened near the College of William and Mary Dillard Complex, prompting an alert from the university. Michelle Anaya provided the information on behalf of Jean Lonchak Danylko's family at a news conference Monday.
It was not immediately clear why North Korean officials had not attended the meeting or whether they had ever confirmed their intention to.
"North Korea apparently wants a US general to appear at the table to quickly finalize the repatriation issue", the source said. Pyongyang has asked the UN Command Armistice Commission to upgrade the talks to a higher level to include a US general, South Korea's foreign ministry said.
KCNA did not say when the trip was made, but Kim Yong Chol, Kim's powerful right-hand man, told a visiting Seoul official last week that the leader was away for a trip to a "local region".
One observer pointed out that Trump would have likely criticized his response to North Korea had it been the reaction of another president.
There was no indication of whether the North Koreans intentionally blew off the meeting.
On Sunday, Pompeo seemingly shrugged off the bombastic statement and said the talks with North Korean officials were conducted in "good faith".