South Korea's top nuclear envoy said Tuesday that the next few months will be "critical" in laying the groundwork for the denuclearization of North Korea and reaffirmed Seoul's commitment to close consultation with Washington both before and after the upcoming inter-Korean summit.

Lee Do-hoon, representative for Korean Peninsula peace and security affairs, made the remarks at the start of the meeting in his office in Seoul with Susan Thornton, acting US assistant secretary of state for East Asian and Pacific Affairs.

"With the inter-Korean summit just a couple of days away, we have a lot to talk about. We believe that the coming weeks and months will be critical in terms of laying the groundwork for the denuclearization of North Korea," he said.

Lee said that in this sense, it is "excellent news" that Mike Pompeo has received the endorsement from a Senate committee, which raised the possibility of his confirmation as the next US secretary of state.

Thornton emphasized that the US is in close coordination with South Korea in dealing with North Korea at a time when the two countries are preparing to hold their respective summits with the North.

"I know you and your colleagues are busy, but I do want to show to your government, our government and the world that we are very closely coordinating and consulting as we always do," she said. "We wish you and your colleagues the greatest success, and we will be keeping in close touch and watching carefully."

Thornton reaffirmed the US' stance to seek a peaceful approach in dealing with North Korea.

Asked if the so-called four no's principle remains valid, she told reporters on her way out, "Sure, I think that is still definitely our position. We focus on denuclearization as our goal."

The four no's refer to the US' commitment not to seek regime change, regime collapse, accelerated reunification and dispatch of troops to the Demilitarized Zone. Former Secretary of State Rex Tillerson made clear that it is the US position in dealing with the North.

Thornton's visit comes as the two Koreas are set to hold a summit Friday, which is expected to be followed by talks between the leaders of the US and North Korea either in May or June.

In a press release issued after the meeting, the foreign ministry said that Lee and Thornton agreed to strengthen close coordination so as to keep the current positive momentum going.

They, in particular, shared the view that the back-to-back summits with the North are "unprecedented opportunities" to denuclearize the North and establish permanent peace on the Korean Peninsula, the ministry said.

Thornton is to leave for Japan late Tuesday after wrapping up a three-day trip to Seoul during which she met high-ranking government officials, including Foreign Minister Kang Kyung-wha. (Yonhap)