Some observers say any wiggle room North Korea may think it has will not last long into 2008, the result of political changes in and among several of the six-party players.

In December South Koreans elected as president a conservative former businessman who won on economic policy but pledged to rethink Seoul's policy of giving unconditional economic aid to North Korea.

President-elect Lee Myung-bak, who takes office in late February, is also committed to reversing the strains the nationalistic populism of his predecessor, Roh Moo-hyun, put on South Korea's ties with the United States and Japan.

Another factor that reduces North Korea's ability to exploit differences among its nuclear negotiating partners is a pragmatic move by Japanese Prime Minister Yasuo Fukuda to promote reconciliation with South Korea and China.

Bruce Klingner, a Korea expert at the Heritage Foundation in Washington, said "2008 looks good for U.S., South Korean and Japanese relations and it also looks good for increasing leverage over North Korea in trying to get them to fully implement their denuclearization pledges."

He said it was understandable that "the U.S. wants to have a reputable declaration, rather than one on time," but it would be wrong to accept less from North Korea in order to score a diplomatic success for the George W. Bush administration.

"Most troubling is that North Korea continues to deny any involvement in a uranium enrichment program and it looks like they're going to declare 30 kg of plutonium rather than the 50 kg the U.S. is confident they've produced," said Klingner.

Fifty kilograms (110 pounds) of plutonium is enough for about eight nuclear weapons.

If North Korea meets the terms of the six-nation deal it will receive one million tonnes of heavy fuel oil or equivalent aid and Washington would take it off its terrorism black list, which could help it tap into international finance.

If it breaks the nuclear pact, the destitute state would miss out not only on aid but on a chance to reinvent itself -- if that's what Pyongyang wants, said Mitchell.

"They do lose, if, as people who are engaging North Korea believe, they are very serious about looking at a different economic model, trying to breaking out of their isolation and having a different relationship with the U.S.," he said.