The United States' point man on North Korea arrived in Seoul Tuesday, calling for "serious negotiations" to ease tensions over Pyongyang's nuclear programme and deadly attack on a South Korean island.
Ambassador Stephen Bosworth, the US special representative for North Korea policy, said he would closely coordinate with South Korea and China on how to deal with North Korea.
"We believe that serious negotiations must be at the heart of any strategy for dealing with North Korea and we look forward to being able to launch those at a reasonably early time," he told reporters at the airport.
China has proposed bringing together the envoys of long-stalled six-nation disarmament talks on the nuclear-armed North to defuse tensions.
But Seoul, Washington and Tokyo have been lukewarm, saying Pyongyang first needs to show it is sincere about denuclearisation and mending ties with Seoul.
"I will let the Chinese speak for themselves on that. I think, by and large, we've been working together with them very effectively. That's an important relationship for both countries," Bosworth said.
The envoy is scheduled to meet his South Korean counterpart, Wiung-Lac, and Foreign Minister Kim Sung-Hwan Wednesday before flying to Beijing.
In November the North sparked security fears by disclosing a uranium enrichment plant to visiting US experts.
It insisted the plant is designed solely to fuel a light-water reactor being built to produce energy. But US officials and experts say this could easily be converted to produce weapons-grade uranium.
The North shut down its elderly plutonium-producing reactor in 2007 under a six-nation deal. But it quit the forum in April 2009 and staged a nuclear test a month later, its second since 2006.
Bosworth's Asia tour, which also includes Tokyo, comes after Seoul reached out to Pyongyang with a signal to open talks after months of high tensions.
North Korea, in a joint New Year editorial by state media on Saturday, said tensions "should be defused as early as possible," stressing dialogue, and that cooperation "should be promoted proactively."
In an apparent response to the North's conciliatory gesture, South Korean President Lee Myung-Bak said Monday that Seoul was open to talks if Pyongyang showed its sincerity towards mending ties.