It will be Pompeo's fourth trip to Pyongyang following two in the spring -- aimed at laying the groundwork for the first summit in Singapore in June -- and a third in July.

The top US diplomat was set for a fourth visit in August, but Trump called it off over what he called a lack of progress in North Korea's denuclearization.

Pompeo posted on Twitter that he had a "very positive" meeting with Ri on the upcoming summit and next steps toward North Korea's denuclearization.

"Much work remains, but we will continue to move forward," he wrote.

Trump and Kim met in Singapore in June to discuss the dismantlement of North Korea's nuclear weapons and ballistic missile programs that pose a direct threat to the United States.

Kim committed to work toward "complete denuclearization" of the Korean Peninsula in exchange for security guarantees from the US

Trump has said he expects to meet Kim soon to follow up on their Singapore summit.

The US has demanded concrete steps, including a full declaration of the North's nuclear arsenal and a timeline for its dismantlement. Kim's regime has insisted on first declaring a formal end to the 1950-53 Korean War, which ended with an armistice, not a peace treaty.

To help break the deadlock, South Korean President Moon Jae-in held his third meeting with Kim last week and secured a commitment from the North Korean leader to permanently shut down a missile testing site in front of international inspectors.

Conditional on reciprocal steps from the US, Kim also committed to dismantling key nuclear facilities.

Trump told reporters at the UN Wednesday that a date and location for the second summit will be announced "in the very near future."

And Pompeo told CBS in an interview that while the meeting could happen in October, it will likely take place after that.

The North Korean foreign minister arrived in New York Tuesday to attend the UN General Assembly, where he is slated to deliver an address Saturday.

Pompeo said in the wake of last week's inter-Korean summit that he had invited the minister to meet with him at the UN gathering.

He also said the North Koreans have been invited to meet with US Special Representative for North Korea Stephen Biegun in Vienna, Austria, presumably to fine-tune the details of the nuclear deal.

This year's UN meeting comes against a backdrop of significantly lowered tensions between the US and North Korea.

In his maiden address to the UN General Assembly last year, Trump threatened to "totally destroy" North Korea and mocked Kim as a "Rocket Man."

The North Korean foreign minister responded that Trump's threat amounted to "the sound of a dog barking" and warned that Kim could detonate a hydrogen bomb over the Pacific Ocean. (Yonhap)