The top U.S. nuclear envoy visited Seoul Thursday for talks with his South Korean counterpart to discuss ways to resume the long-stalled negotiations aimed at ending North Korea’s nuclear program, Seoul’s Foreign Ministry said.

Sung Kim, a former U.S. ambassador to South Korea, arrived in Seoul later in the day to meet with Hwang Joon-kook, special representative for peace and security affairs on the Korean Peninsula, a day later, the ministry added.

It marks his first visit to Seoul with his current title amid a flurry of diplomatic efforts to restart the six-party talks on denuclearizing North Korea.

The main agenda for Kim’s talks with Hwang is said to include a recent visit to Russia by Choe Ryong-hae, a special envoy of North Korean leader Kim Jong-un. Choe told Russian officials that Pyongyang is willing to resume the talks without preconditions.

The six-party talks involving the two Koreas, the U.S., China, Russia and Japan have been stalled since late 2008, when Pyongyang walked away from the negotiating table.

Seoul and Washington have demanded the North first take concrete steps demonstrating its commitment to denuclearization.

China, a traditional ally of the North, has insisted that South Korea and the U.S. should lower the bar for the talks.

Pyongyang’s recent release of all three Americans detained in North Korea has been widely seen as aimed at securing bilateral dialogue with Washington, analysts say. The U.S. has said that it offered no concessions for their release.

Kim’s planned visit also came amid reports that North Korean government officials and U.S. security experts are looking into a possible meeting in Singapore next month.

South Korea’s top nuclear envoy Hwang, meanwhile, was to return to Seoul later in the day after wrapping up a four-day trip to Russia that began on Monday to discuss the North’s nuclear issue.

Hwang told reporters in Moscow that Seoul is prepared to resume the six-party talks if the North shows strong signs that it will have “constructive dialogue” for denuclearization.

Kim, a career diplomat with expertise on the North Korean nuclear issue, took office last month as the top U.S. negotiator for the six-party talks after completing a three-year stint as ambassador to Seoul. Kim also doubles as deputy assistant secretary for Korea and Japan.

Kim’s regional trip also includes three-day stops each in Japan and China. He will leave for Japan on Monday for a three-day visit.

Kim will then visit Beijing on Dec. 10 for talks with his Chinese counterpart Wu Dawei. (Yonhap)