US President Donald Trump released on Thursday a letter he had received from North Korean leader Kim Jong Un in which he calls on the American leader build trust. "A very nice note from Chairman Kim of North Korea," Trump tweeted alongside a copy of the letter dated July 6 -- the day that US Secretary of State Mike Pompeo landed in Pyongyang for what turned out to be difficult talks with Kims regime. "Great progress being made!" Trump added in his tweet. In the letter Kim describes his June 12 summit with Trump in Singapore, and the resulting joint statement agreed by both sides, as the "start of a meaningful journey." "I firmly believe that the strong will, sincere efforts and unique approach of myself and Your Excellency Mr. President aimed at opening up a new future between the DPRK and the US will sure surely come to fruition," Kim writes. "I deeply appreciate the 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," he adds. The North Korean leader also voices hope that "the invariable trust and confidence in Your Excellency Mr. President will be further strengthened in the future process of taking practical actions." Pompeo traveled to Pyongyang for two days last week in a bid to flesh out denuclearization commitments made during last months historic summit between Trump and Kim. North Korea has long trumpeted a denuclearization goal, but one that it sees as a lengthy process of undefined multilateral disarmament on the entire Korean peninsula, rather than a unilateral dismantlement of its nuclear arsenal. Speaking afterwards in Tokyo, Pompeo insisted the talks were making progress and were being conducted in "good faith." But in stark contrast, Pyongyangs take was overwhelmingly negative, with the North warning that the future of the peace process was being jeopardized by overbearing US demands for its unilateral nuclear disarmament. Earlier on Thursday, the US asked the UN Security Council to order an immediate halt to all deliveries of refined oil products to North Korea after finding that Pyongyang had violated restrictions on those imports, according to documents seen by AFP on Thursday. A confidential US report sent to a UN sanctions committee estimated that at least 759,793 barrels of oil products had been delivered to North Korea between January 1 and May 30, well above the annual quota set at 500,000 barrels. The illegal supplies were provided through ship-to-ship transfers at sea using North Korean tankers that have called in port at least 89 times "likely to deliver" the shipments, according to the report. The United States requested in a letter that the UN sanctions committee declare that North Korea had violated the UN-approved quota and "order an immediate halt to all transfers of refined petroleum products" to North Korea. The committee was expected to take five days to consider the request, which China and Russia are expected to block.