He attributed the sudden cancellation to "trips that are being made," but did not elaborate.

"We think it's going fine," Trump said. "We're in no rush. We're in no hurry. The sanctions are still on."

Pompeo and Kim Yong-chol, a close aide to the North Korean leader, were expected to continue talks on dismantling the regime's nuclear weapons program and arranging a second summit between the leader and Trump.

Asked if he still plans to have the second summit, the US president said, "Sometime next year, I would say. Sometime early next year."

The State Department provided no explanation for the meeting's postponement.

In a statement released at midnight, the department said the two sides "will reconvene when our respective schedules permit."

"Ongoing conversations continue to take place," it said. "The United States remains focused on fulfilling the commitments agreed to by President Trump and Chairman Kim at the Singapore Summit in June."

The Singapore summit was the first meeting between Trump and Kim, who committed to work toward "complete" denuclearization of the Korean Peninsula in exchange for security guarantees from the US

The abrupt rescheduling raises questions about the prospects for continued negotiations between Washington and Pyongyang.

North Korea has increasingly called for sanctions relief in return for its denuclearization steps, but the US has refused to comply until the full and verified denuclearization of the regime.

Trump said Wednesday that he would "love to take the sanctions off, but they have to be responsive, too."

In August, Trump canceled Pompeo's planned trip to Pyongyang, citing a lack of progress in North Korea's denuclearization.

Before that he also called off the Singapore summit before putting it back on.

That decision came after Kim Yong-chol met with Pompeo in New York in May. At the time, Kim also traveled to Washington to deliver a personal letter from the North Korean leader to Trump at the White House.

Speaking at a regular press briefing, State Department deputy spokesperson Robert Palladino emphasized that the postponement was "purely a matter of scheduling."

"Schedules change all the time," he said. "Everything else remains completely on track." (Yonhap)