Thomas Maresca

Special to USA TODAY

SEOUL — North Korea sent a warning to the U.S. on Thursday to avoid “meddling” in its affairs with South Korea and criticized Washington’s “unreasonable attitude” and “hostile” policies.

An editorial in the country’s state-run Rodong Sinmun newspaper blamed the U.S. for stagnation in the relationship between North and South Korea, claiming that “the United States does not want to see the improvement and development of the inter-Korean relations.”

While relations between Pyongyang and Washington remain at an impasse over North Korea’s nuclear disarmament and the lifting of international sanctions, Seoul has been pushing forward in peace gestures and engagement with the North.

The two Koreas have removed 10 guard posts in the demilitarized zone that divides the peninsula and recently held a groundbreaking ceremony on a project to connect their railroad systems. But that project and others like it cannot move much further until the U.S.-led sanctions on North Korea are lifted.

The North has also been eager to reopen a jointly run factory park in its border town of Kaesong and to resume South Korean tours to the resort area of Mount Kumgang.

“We will never tolerate the intervention and interference of the U.S. that tries to check the Korean nation's reconciliation, unity and reunification while trying to subordinate the north-south relations to its own tastes and interests,” said the editorial.

“This is our warning in New Year,” the article concluded.

The sharp words came just a day after President Donald Trump said that he had received a “great letter” from North Korean leader Kim Jong Un and that the two would like to meet for a second time.

More:North Korea warns US sanctions could 'block the path to denuclearization forever'

Speaking to reporters during a Cabinet meeting at the White House on Wednesday, Trump said that he and Kim have made “tremendous progress” and have “really established a good relationship.” He also claimed credit for maintaining peace on the Korean peninsula, saying that if it weren’t for the efforts of his administration, “you’d be having a nice, big, fat war in Asia.”

However, Trump said he wasn’t “in any rush” to hold the second meeting.

Trump has frequently praised Kim, saying in September that the North's leader was “terrific” and that the two “fell in love” after their historic summit in Singapore last June.

That summit produced an agreement that North Korea would work toward a “complete denuclearization of the Korean Peninsula,” while the U.S. promised to provide security guarantees.

But more than six months later, there has been little tangible progress.

Pyongyang continues to look for relief from punishing international sanctions and an agreement for a formal end to the Korean War, while Washington is holding out for complete denuclearization, sticking to its “maximum pressure” strategy on the economic and diplomatic fronts.

In a televised New Year's Day address, Kim said he was ready to meet again with Trump “anytime” but delivered a warning not to test North Korea’s patience over sanctions, threatening that it may have to find a “new way” to defend its interests.

If the U.S. “persists in imposing sanctions and pressure against our Republic, we may be compelled to find a new way for defending the sovereignty of the country and the supreme interests of the state,” Kim said.