North Korean leader Kim Jong Un praised Donald Trump in a letter written before US-North Korean talks hit a snag last week, saying the US president's "energetic and extraordinary efforts" in reshaping ties between the two countries will help create a "new future".
Secretary of State Mike Pompeo was in North Korea last week and took along a copy of the British singer's CD with the "Rocket Man" song that Trump had signed, but Pompeo did not meet with Kim this time around so he brought the gifts back to the president.
Pompeo had visited Pyongyang last week in a bid to ease any misunderstandings between the two parties and find areas where they could make progress.
The secretary of state did not meet Kim as he had on his previous two trips to Pyongyang this year, and after his departure, the North's foreign ministry accused the USA of making "gangster-like" demands that it unilaterally give up its nuclear weapons.
Pompeo also said sanctions would remain in place until "a final fully verified denuclearization" that he said Kim had agreed to occurred.
In another sign that relations have strained since Kim sent the letter, CNN reported that North Korean officials failed to show up for a meeting with their us counterparts in the demilitarized zone Thursday.
Following the North Koreans' no-show at Thursday's meeting, the U.S. state department said the two delegations had agreed to meet on 15 July.
That meeting concluded with North Korean state media calling the USA approach "cancerous" and "gangster-like".
"This step will build trust & confidence btw US & DPRK", he tweeted on Monday, using the acronym for North Korea's official name. "Great progress being made".
"We had a productive conversation", the USA top diplomat said, but added, "There remains a great deal of work to do". The meeting was later rescheduled for July 15, according to South Korean officials.
NATO leaders on Wednesday called on all nations to maintain "decisive pressure" on North Korea, including by fully implementing United Nations sanctions, to persuade it to give up it nuclear, chemical and biological weapons.
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.
An estimated 30,000 USA soldiers died in the 1950-53 Korean war.
The U.S. says North Korea has continued to smuggle refined petroleum products into the country in excess of the quota of 500,000 barrels per year allowed under United Nations sanctions imposed because of nuclear and missile programs.
However, according to the U.S. State Department, . the North contacted the U.S. side, offering to hold the talks on Sunday instead. It recoiled at what it described as a "unilateral and gangster-like demand for denuclearization". They signed a joint statement reaffirming North Korea's commitment to giving up nuclear weapons.