South Korean President Moon Jae-in said on Thursday that North Korea's criticism of the United States after recent talks on denuclearisation was part of its strategy and negotiations between them are on the "right track".
The fact that Kim Jong Un's letter says Trump took "energetic and extraordinary" efforts, it's most telling that Un admits only to taking "future process of taking practical actions", but says nothing of what was achieved during the Trump-Kim Summit.
The BBC reported speculation that North Korea may want payment for the return of the remains.
When Trump and Kim held their historic summit in Singapore on June 12, Kim - in addition to promising, in vague terms, to work toward the denuclearisation of the Korean Peninsula - committed to returning the remains of U.S. troops recovered from major Korean War battle sites in his country, including the "immediate repatriation of those already identified".
It said this had been done through ship-to-ship transfers at sea using 89 North Korean tankers.
Kim committed to a nuclear-free North Korea at the end of the convivial meeting, but tensions resurfaced in the following weeks as representatives of both countries began to flesh out the deal.
The Pentagon says Pyongyang has indicated several times they have as many as 200 sets of remains that could be those of U.S. soldiers who died in the war.
Separately, North Korean officials did not show up at planned talks with the USA on Thursday to discuss repatriating the remains of American soldiers killed during the 1950-53 Korean War.
Their meeting - the first between a sitting USA president and North Korea, led to claims that the latter would work towards dumping its nuclear weapons.
Trump was in London to meet with United Kingdom leaders after leaving the North Atlantic Treaty Organisation summit in Brussels, Belgium, when he tweeted Kim's letter.
If realized, they will be the first general-level military talks between North Korea and the UNC since March 2009.
North Korea proposed to reschedule the meeting for Sunday. -North Korea relations, despite signs that path-finding diplomacy between the adversaries is running into problems.
According to a copy of the report seen by The Washington Post, U.S. officials calculated that even if the tankers carried only one-third of their full load, North Korea would have already exceeded the annual quota of 500,000 barrels allowed under United Nations sanctions.
"The road ahead will be hard and challenging and we know that critics will try to minimize the work that we've achieved", he said.