By Paul Reynolds
World affairs correspondent, BBC News website
North Korea is believed to be restoring the Yongbyon nuclear facility
North Korea's offer to return to talks about its nuclear programme has been met with scepticism by regional and Western experts.
The offer - to talk to the US bilaterally first before possibly rejoining the six-party talks it renounced earlier this year - came during a visit by the Chinese Prime Minister Wen Jiabao.
The suspicion is that Mr Wen twisted the arm of the North Korean leader Kim Jong-il.
"There is no doubt that Wen delivered a very clear-cut message. China wanted to give a push," said Zhu Feng, professor of international security at Peking University.
"The key question is not just how to bring them back to the negotiating table but also how to change their behaviour," he told Reuters news agency.
In London, Mark Fitzpatrick of the International Institute for Strategic Studies doubted whether North Korea would change its behaviour significantly.
"I am sceptical. I do not think that North Korea wants to give up its nuclear weapons. The North might even want the US to accept it as a nuclear state."
If this is so, then the challenge is to manage the always-present crisis with North Korea because it cannot be solved.
The S words
The key to understanding North Korea might well be the two S words.
The first is survival - the survival of the system and its leaders. That requires a strong defence, of which nuclear is the most powerful and attractive - justified by a constant refrain that the country is under threat.
The second is the military-first philosophy called "songun".
This has been emphasised under Kim Jong-il and basically requires that the military is the most important state organ and gets first pick of everything.
Songun would appear to preclude the idea of giving up nuclear weapons.
The United States maintains as its goal the denuclearisation of the whole Korean peninsula and will not unilaterally accept North Korea as a nuclear state. Its regional partners, especially Japan and South Korea, would be alarmed if it did.
As for direct talks, President Barack Obama's special envoy on North Korea, Stephen Bosworth, said in September that the United States was "willing to engage with North Korea on a bilateral basis".
But, he added: "We do not consider in any way that bilateral engagement is a substitute for multilateral engagement, and this is not a substitute for us for the re-ignition of the six-party talks."
Restoring a reactor
South Korean sources say in addition that North Korea has now reached the final stages of restoring the Yongbyon nuclear facility it had begun to disable after earlier six-party talks in 2007.
This development also casts doubt on North Korea's intentions.
And according to an American scientist who was invited to Yongbyon with a colleague over a period of five years, the North perhaps always intended to be able to put Yongbyon back together again.
The military gets the first pick of everything in North Korea
The scientist, Stanford University Professor Siegfried S Hecker, a former director of the Los Alamos laboratory, wrote in the Bulletin of the Atomic Scientists in May: "I believe that North Korea can restore operations at all three of the [Yongbyon] facilities if it so chooses.
"Pyongyang had always interpreted the disablement process as making it more difficult, but not impossible to return to plutonium production."
If that is the case, the North's motives in agreeing to the disablement in the first place must be suspect.
It was perhaps always planning for a reversal of its position and the restoration of Yongbyon.
The confrontation between itself and the UN over its ballistic missile test in April this year, followed by its second nuclear test in May and further UN sanctions, might have offered it a good opportunity to take a step backwards.