SEOUL, June 4 (UPI) -- Nearly one year after a historic Singapore summit between President Donald Trump and North Korean leader Kim Jong Un, the Asian nation advised the United States to change its approach in nuclear negotiations and warned that its patience has limits.
"The U.S. would be well-advised to change its current method of calculation," an unnamed spokesman for North Korea's ministry of foreign affairs said Tuesday night in a statement carried by state-run Korean Central News Agency.
"There is a limit to our patience," he added.
Calling the June 12, 2018, summit between Trump and Kim a "momentous occasion of great significance in promoting peace and stability on the Korean Peninsula," the spokesman said that North Korea has "exerted ceaseless efforts over the past year" to fulfill the joint statement produced there.
The Singapore joint declaration called for establishing new relations between the two countries and building a "peace regime" on the Korean Peninsula. It also said that North Korea would work toward a "complete denuclearization of the Korean peninsula," but did not produce a timeline or details on implementation.
The North Korean spokesman accused the United States of not playing its part in carrying out the agreement, saying that it is "regrettable to see that the United States has become ever more undisguised during the past year in its scheme to annihilate us by force."
He claimed that that the United States has insisted "on our unilateral surrender of nuclear weapons."
Pyongyang has been looking for a gradual approach in negotiations, seeking relief of international sanctions in exchange for steps it has already taken, such as dismantling a nuclear testing site, while Washington has continued to hold out for complete denuclearization before any concessions are made.
A second Trump-Kim summit, held in February in Hanoi, concluded abruptly without an agreement and in recent weeks North Korea has sought to increase pressure on the United States to change its stance.
In an April speech, Kim set a time limit, saying Washington should come up "with a proper method of calculation before the end of this year."
Tensions have also flared recently as North Korea launched what the Pentagon said were short-range ballistic missiles on May 4 and May 9 and the United States announced it had seized a North Korean cargo ship on suspicion it violated sanctions.
North Korea called the act a "robbery" and demanded the ship's immediate return.
Trump has said that he is open to meeting with Kim again and tweeted last month that he believed a deal would still go forward.
"We're working to find a negotiated solution so that Kim Jong Un will honor the commitment that he made, the commitment he made to his own people and the commitment he made to President Trump in Singapore, to denuclearize his country," Pompeo said.
However, the North Korean spokesman said that it remains to be seen whether the June 12 joint statement "will remain effective or turn out to be a mere blank sheet of paper."
"The U.S. should duly look back on the past one year and cogitate about which will be a correct strategic choice before it is too late," he said.