In Beijing, the six-party talks on North Korea's nuclear-weapons program have resumed.

The United States has been saying since October 2002 that Pyongyang has a secret nuclear-weapons program. Since then, North Korea has pulled out of the Nuclear Non-Proliferation Treaty, expelled U.N. monitors, and re-opened a nuclear facility it had promised to dismantle in 1994.

Jim Walsh is a nuclear expert from Harvard University says very little is known about North Korea's program to build nuclear weapons.

"It is not a very transparent place. International Atomic Energy Agency inspectors have not been there for some time. But what is known from the past, is that they had a reactor that could produce plutonium, that could reprocess plutonium and with that plutonium, construct nuclear weapons," he said. "On February 10 of this year, the North Korean government issued an announcement saying that they had nuclear weapons: that was their first public pronouncement of that kind, although they had been telling us and others privately four months prior to that that they did in fact have a quote 'nuclear deterrent' unquote. But the estimates are uncertain, ranging anywhere from zero nuclear weapons to maybe six to eight nuclear weapons, but frankly, not a lot is known. They have not tested a nuclear weapon, so there is not a lot of data out there."

For the past several years, the United States has been trying to persuade North Korea to eliminate its nuclear-weapons capabilities. That effort has been conducted through the negotiating forum known as the six-party talks that bring together the United States, China, Russia, Japan, South Korea, and North Korea.

Since August 2003, diplomats from the six countries met three times with very little progress achieved. Now, after a 13-month hiatus, the parties are meeting again in an effort to try to move the process forward.

Experts say it will not be easy to reconcile two conflicting negotiating positions.

"What is clear from the historical record, is that what North Korea seems to be looking for is a resolution to the long-standing 'state of war' that technically and legally still exists between North Korea and the United States," said Daryl Kimball, who heads the Arms Control Association, an independent research organization. "This is why they have from time to time said that they seek some form of peace treaty with the United States, to formally end the Korean War. They also, related to that, have stated that they are looking for guarantees that the United States will not attack the regime or the country."

During the opening round of talks earlier this week, chief U.S. negotiator Christopher Hill said the Bush administration had no plans to attack North Korea.

Experts also say Pyongyang is looking for economic incentives in exchange for nuclear disarmament. Mr. Kimball says the United States wants something else from North Korea.

"For the North Koreans to announce that they are going to dismantle their nuclear-weapons capacity, to freeze their current activities in a verifiable fashion, both in terms of their plutonium activities and their possible uranium-enrichment activities and then allow for the dismantlement of their nuclear facilities that can be used to produce nuclear bomb material or nuclear weapons," he said.

Mr. Kimball says a key sticking point in the negotiations is what is called "sequencing", what comes first, North Korea's disarmament or economic incentives from neighboring states?

"The North Koreans want all the benefits up front and they would like to dismantle later. And what the United States has been has been insisting on, up to this point, basically, is for the North Koreans to announce that they are going to dismantle and to begin doing so and then to consider providing some of the benefits the North Koreans are looking for," he explained. "So I think to put it crudely, bluntly, simply - one of the key, if not the key, issue for the two sides to resolve is the sequencing of these steps."

Harvard University's Jim Walsh, who has recently met with North Korean nuclear officials in Pyongyang, says there is another key factor that will determine the success or failure of these talks.

"The real issue here, the more general issue is an issue of seriousness. And the North Koreans wonder whether the United States is really serious or whether it is talking for the sake of talking, for diplomatic advantage or to buy time," said Mr. Walsh. "For their part, American officials wonder whether the North Koreans are serious, whether they are just talking for the sake of talking in order to get aid or other assistance. And so while I do not expect at this week's talks for there to be a major breakthrough - I do not expect the difficult issues to be resolved. I do hope, though, that each side is able to communicate to the other, in a credible way, that they are serious and want real negotiations."

Analysts say if these talks fail, the United States may call for economic and political sanctions against North Korea, including referring the matter to the United Nations Security Council. Experts say that would result in an unfortunate escalation of the crisis with unforeseen consequences for everyone.