North Korean officials did not turn up to a Thursday meeting with the USA military about repatriating the remains of American war dead, according to a US official with knowledge of the situation.
But there have been several meetings between senior officials since, including a visit to North Korea by Secretary of State Mike Pompeo earlier in July which failed to make any progress on denuclearisation.
Meanwhile, agencies reported that United States asked the UN Security Council to take punitive measures against North Korea for violating restrictions on refined oil imports.
Trump has repeatedly voiced optimism that Kim will dismantle the regime's nuclear weapons program despite recent news reports that North Korea continues to expand its nuclear facilities.
North Korea's leader, Kim Jong-Un, has written a note to U.S. President Donald Trump, describing the American leader as "energetic and extraordinary".
That meeting concluded with North Korean state media calling the USA approach "cancerous" and "gangster-like".
According to a copy of the report seen by The WashingtonPost, 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 Nationssanctions.
Under the latest sanctions resolution adopted in December, crude oil supplies to North Korea were capped at four million barrels per year and a ceiling of 500,000 barrels of refined oil products per year was set.
A major sticking point between the two sides has been Washington's plan for North Korea's complete, verifiable and irreversible denuclearization.
This is the first yank on the choke chain, in other words. Let's have a look, shall we?
The delay has fuelled growing doubts about the success of the Singapore summit.
While visiting Pyongyang last week, Mr Pompeo said that a Pentagon team would meet with the North's officials in or around Panmunjon - the truce village on the border between North and South Korea.
"Repatriation of USA remains from North Korea will be important not just to American families, but to building trust between the US and North Korea as well", Pompeo said earlier this week.
In a post on Twitter, Mr Trump said the letter, dated July 6, was very nice and was a sign of "Great progress being made!".
Despite such setbacks, Trump has continued to maintain that progress is being made.
That's a clever counterpoint to the yank on the choke chain.
It was "a sacred land of the revolution", Kim said, which authorities were seeking to build "into a model of the country and fairyland of communism".
If nothing else, though, this tightening of sanctions demonstrates that the Trump administration is far from giving away the store to Kim. "Mr. Chairman, it's a great honor to be with you, and I know we'll have tremendous success together and we'll solve a big problem-a big dilemma-that until this point has been unable to be solved, and working together we'll get it taken care of", the president said during the meeting.