Assistant Secretary of State James Kelly made the comment after meeting the South Korean foreign and unification ministers in Seoul even as Deputy Secretary of State Richard Amritage said in Tokyo that a second round of six-way negotiations could resume soon.
"Mr Kelly noted that the inter-Korea talks play the underpinning role in the effort to resolve the North Korean
nuclear programme," South Korean Unification Ministry official, Park Chan-bong, said.
Unification Minister Jeong Se-hyun hosts a North Korean delegation for talks beginning on Tuesday in Seoul.
For four days, the focus of the effort to bring North Korea to the negotiating table shifts from diplomats to the highest-running channel of dialogue between the two Koreas.
"It is a dangerous and unstable situation in one of the most dynamic and heavily populated areas of the world. The stakes are too high. We simply cannot allow the situation to continue to slide in the wrong direction"
US Deputy Secretary of State
Jeong's ministry pursues economic and humanitarian cooperation with the North under Seoul's policy of
rapprochement with its communist neighbour.
Foreign Minister Ban Ki-moon echoed mounting optimism that the six countries - which also include China, Japan and Russia - will be able to meet soon.
"It is our position to use this ministerial meeting between the South and the North to have more intensive discussions in a way conducive to a successful second round of meetings," he said.
US Deputy Secretary of State Richard Armitage said on Monday that six-way talks could take place soon even as he termed the stalemate a "dangerous and unstable situation".
One round of talks took place last summer in Beijing, but ended inconclusively.
Armitage (C) hopes that the next
round of talks will be held soon
"It is a dangerous and unstable situation in one of the most dynamic and heavily populated areas of the world," Armitage, who is in Japan for strategic talks, said.
"The stakes are too high. We simply cannot allow the situation to continue to slide in the wrong direction."
Asked about the timing of a new round, Armitage said: "I think that talks will take place soon... I think we will be having them soon and it will come clear in the near future."
Despite months of diplomacy, the various parties have failed to reach an agreement on when to hold a follow-up round.
Armitage said that the talks would probably not take place by mid-February.
"I will note that mid-February, the 16th of February is the birthday of (North Korean leader) Kim Jong-il and I don't think it's very likely that we'll be celebrating his birthday by having six-party talks," he said.
The US wants North Korea - at least by the end of the next round - to commit to dismantling any nuclear arms programmes.
Washington has offered to then lay out in detail how it could guarantee that it would not attack the country, which US President George Bush has labelled part of an "axis of evil".
The crisis over North Korea's nuclear programme erupted in October 2002 when US officials said Pyongyang had admitted to pursuing a clandestine weapons programme.