The US has invited North Korean officials to meet with the new US special representative for North Korea, Stephen Biegun, in Vienna, Austria, "at the earliest opportunity," he said.

Biegun has been tasked with leading negotiations with Pyongyang to implement an agreement reached by US President Donald Trump and Kim at their historic Singapore summit in June.

In that agreement, Kim committed to work toward "complete denuclearization" of the Korean Peninsula in exchange for security guarantees from the US But progress on the deal stalled as each side demanded the other move first.

The Trump administration has sought concrete denuclearization steps, such as an inventory of the North's nuclear arsenal and a timeline for the nuclear program's dismantlement. Pyongyang has instead pushed the US to jointly declare an end to the 1950-53 Korean War, which ended only with an armistice and left the two sides technically still at war.

Pompeo said the proposed Vienna meeting will "mark the beginning of negotiations to transform US-DPRK relations through the process of rapid denuclearization of North Korea, to be completed by January 2021, as committed by Chairman Kim, and to construct a lasting and stable peace regime on the Korean Peninsula."

The Trump-Kim summit agreement committed the two nations to establish "new US-DPRK relations" in accordance with their peoples' wishes for peace and prosperity.

And in a meeting with a South Korean presidential delegation this month, Kim was quoted as saying he would like to achieve the peninsula's denuclearization before the end of Trump's first term.

Pompeo said he invited North Korean Foreign Minister Ri Yong-ho in the morning to meet him in New York next week on the sidelines of the United Nations General Assembly, which they are both scheduled to attend.

Trump welcomed the outcome of the inter-Korean summit.

"Kim Jong Un has agreed to allow Nuclear inspections, subject to final negotiations, and to permanently dismantle a test site and launch pad in the presence of international experts," he wrote on Twitter, adding that it was "very exciting" that the two Koreas had agreed to file a bid to jointly host the 2032 Olympics.

He later told reporters at the White House that there was "very good news" from South and North Korea.

"They met, and we had some great responses," he said before leaving for hurricane-hit North Carolina. "I got a tremendous letter from Kim Jong-un. As you know, it was delivered three days ago. We're making tremendous progress with respect to North Korea."

The White House said early last week that Trump had received a letter from Kim in which the North Korean leader requested a second meeting between the two. Planning for that meeting is already underway, White House press secretary Sarah Sanders said.

"Well, we'll see what he's looking at," Trump said when asked what corresponding measures Kim could be seeking. "We'll see. But in the meantime, we're talking. It's very calm. He's calm. I'm calm. So we'll see what happens. Okay?"

The recent developments stand in stark contrast to last year when tensions soared as Trump and Kim engaged in a war of words over North Korea's testing of nuclear weapons and intercontinental ballistic missiles capable of reaching the US

Trump threatened to "totally destroy" the regime and mocked Kim with the nickname "Little Rocket Man." The North Korean leader called Trump a "mentally deranged US dotard."

Asked if he will be meeting Kim soon, Trump responded, "We will be." (Yonhap)