WASHINGTON - North Korea faced no outcry on Monday when it failed to account for its nuclear programs by an agreed year-end deadline, but Pyongyang might not be able to procrastinate for long in 2008.

North Korea was widely expected to miss the December 31 target date to produce a complete declaration of its nuclear arms programs -- facilities, weapons and fissile material -- under a disarmament-for-aid deal signed 10 months earlier.

The secretive state -- which since the 1980s has broken or ignored nuclear-related understandings with the Soviet Union, South Korea, the International Atomic Energy Agency and the United States -- received only the mildest of rebukes.

U.S. State Department spokesman Tom Casey called the lapsed deadline unfortunate but said the United States and partners China, Japan, Russia and South Korea would keep working with North Korea.

"We've seen these kinds of delays or other things occur in the process as we move along, and in some ways I think you have expect those things," he said.

White House spokesman Scott Stanzel said, "We think it's possible for the North Koreans to provide a full and complete declaration and we hope they will do that as soon as possible."

Experts said they expected North Korea to be cut some slack after a year in which the goalposts were moved several times to keep diplomacy on track. The North had already crossed a major line when it tested a nuclear bomb in October 2006.

The Americans "were always ready, knowing North Korea, to roll for a month or two, but the real questions come after that. At what point do they make a judgment on the seriousness of North Korea about this whole endeavor?" asked Derek Mitchell of the Center for Strategic and International Studies.

The declaration deadline follows relatively smooth cooperation in late 2007 with North Korea in disabling its aging Yongbyon nuclear complex, which is also required under the nuclear deal.

NEW LEVERAGE IN 2008?

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.