By Jeremy Laurence
SEOUL (Reuters) - A rare visit by one of North Korea's top diplomats to the United States this week has renewed hopes for stalled nuclear talks, but Seoul and Washington's terms have not changed: Pyongyang has to show it is sincere about scrapping its atomic bomb.
North Korea's Vice Foreign Minister Kim Kae-gwan travels to New York at the end of the week in what will be the first such contact between the sides since a visit by Stephen Bosworth, the top U.S. envoy on peninsula affairs, to Pyongyang in 2009.
His visit comes on the heels of the first meetings in more than two years between the two Koreas' nuclear envoys and foreign ministers last week, defusing tensions and raising hopes for a restart of the long-delayed six-party talks.
The secretive North stormed out of aid-for-denuclearization talks in 2009 after the United Nations imposed a new round of sanctions for conducting nuclear and missile tests, but has since said it wants to rejoin the forum.
Relations on the peninsula crashed to their lowest level in nearly two decades last year after two deadly attacks killed 50 South Koreans, and only a few weeks ago the North swore it would never again negotiate with Seoul's conservative government.
"North Korea's reversal is dramatic but the U.S. and South Korea remain properly suspicious that Pyongyang has no intention of actually fulfilling its denuclearization commitments," Bruce Klingner, of the Washington-based Heritage Foundation think tank, told Reuters.
"Vague promises simply to 'make efforts to resume six-party talks' are not grounds for exuberant optimism."
Seoul and Washington are adamant their terms have not changed for the resumption of six-party talks, which also involve China, Russia and Japan.
U.S. Assistant Secretary of State Kurt Campbell said on Monday this week's talks were "preliminary" and should not necessarily be seen as a move toward restarting six-party talks.
"We have very clear pre-steps related to nuclear issues, related to proliferation concerns, that we will need to see clearly articulated by the North Koreans if we are to go forward," he said.
A South Korean presidential aide, who asked not to be named, said: "We are ready to talk with them anytime and anywhere only if the North shows its willingness to abandon its nuclear weapons development program."
Washington and Seoul say North Korea has repeatedly rowed back on promises made in a series of denuclearization deals over the past two decades.
This time, they say, Pyongyang must take concrete steps to demonstrate it is serious. Analysts say such a step would be to allow the return of international nuclear inspectors who were expelled in 2009.
In return for disabling its nuclear program, which has already produced up to 10 atomic bombs, the North would receive economic aid, diplomatic recognition from the United States and a formal treaty to end the Korean War.
But analysts say there is next to no chance the recalcitrant state will ever give up its nuclear bombs because they are the ultimate deterrent against attack by the United States and the South, and also its biggest bargaining chip in negotiations.
PUSH FOR ECONOMIC AID
Analysts say pressure from China and the United States has driven the destitute North back to the negotiating table, and that Pyongyang will probably use dialogue as a platform to seek aid as it battles a food crisis.
"Pyongyang leaders needs concessions, largely of monetary nature," says Andrei Lankov of Kookmin University in Seoul. "If they are not getting what they want, they will switch to confrontational mood again."
Experts agree the talks themselves serve a purpose even if the end-goal of complete denuclearization is unattainable while Kim Jong-il maintains his iron rule.
They say the North's willingness to talk with the United States lowers tensions in northeast Asia, responsible for about one-sixth of the global economy.
Victor Cha, a North Korea expert from Georgetown University in the United States, tracked 60 years of U.S.-North Korea dialogue, and found that when they were talking Pyongyang did not resort to acts of aggression, or so-called provocations.
"This report has apparently resonated in the administration and animated the discussions about re-engaging the North," said Michael Green, a colleague at Georgetown.
(Additional reporting by Sung-won Shim; Editing by Alex Richardson)