US officials and experts have said the shift in attitude was to be expected as the North Koreans are known for brinkmanship and trying to up the ante ahead of tough negotiations over their nuclear missile program.
"We call upon (North Korea) to fully implement its global obligations; to eliminate its nuclear, chemical, and biological warfare capabilities and ballistic missiles, and abandon all related 'programs", the statement said.
It had been expected on Thursday at the inter-Korean truce village of Panmunjom.
Kim Jong Un had committed to returning the remains of the troops from the 1950-53 conflict during talks with US President Donald Trump on 12 June.
And last weekend U.S. Secretary of State Mike Pompeo flew to Pyongyang to follow up on that and other agreements, including North Korea's commitment to the "complete denuclearization" of the Korean Peninsula. 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 Korean war.
"Mid-day, on July the 12th, they contacted us and offered to meet on Sunday, July 15", Nauert said in a statement, adding "We'll be ready".
The following day an unsigned statement from the agency accused the USA of operating under a "gangster-like mindset".
Currently, Pyongyang has no formal ties with either the United States or Japan - the top two voting powers in the International Monetary Fund and the World Bank - whose endorsements North Korea must have to join the institutions.
It's unclear why the North Korean officials were not present.
The United States requested in a letter that the U.N. sanctions committee declare that North Korea had violated the U.N. -approved quota and "order an immediate halt to all transfers of refined petroleum products" to North Korea.
Moon said North Korea wanted the United States to take action to end hostile relations and build trust.
"North Korea would have to deal with the consequences of breaking away from the negotiations if it were to do so, so it will likely not make an extreme decision", Kim said.
The Trump administration has insisted that progress is being made.
As well as tweeting the letter from Mr Kim, Mr Trump also found time after arriving in the United Kingdom to tweet pictures of him emerging from Air Force One at Stansted and an article praising his impact in lowering unemployment among minorities in the US.
Germany's Chancellor Angela Merkel, Canadian Prime Minister Justin Trudeau, NATO Secretary-General Jens Stoltenberg and Italian Prime Minister Giuseppe Conte are seen at NATO headquarters in Brussels, Belgium, July 11, 2018.
Kim, in his note, praised Trump for "energetic and extraordinary efforts made by Your Excellency Mr. President for the improvement of relations between the two countries and the faithful implementation of the joint statement".