It is more than four years since North Korea, the United States and four other nations sat down to begin discussing a possible end to North Korea's nuclear programs. While there is still a long way to go before that goal becomes a reality, an unprecedented step in that direction is about to be taken on Monday. Barry Kalb reports from our Asia News Center in Hong Kong.

There have been repeated delays in the six-party talks on North Korea's nuclear programs. There were times when it looked like there was no chance Pyongyang would ever be convinced to shut those programs down.

In just a few days from now, however, a preliminary but unprecedented step in that direction is due to be taken.

A team of U.S. nuclear experts is now in North Korea to oversee the disabling of the North's main nuclear complex, at Yongbyon.

U.S. nuclear envoy Christopher Hill talks to journalists gathered at a hotel in Beijing, 30 Oct 2007

The chief U.S. envoy to the six-party talks, Assistant Secretary of State Christopher Hill, has always been hesitant to sound too optimistic about the talks. But addressing reporters in Tokyo Saturday, Hill was able to report some real progress.

"This will be the first time those facilities have ever been disabled. And of course the idea of disablement is to create a situation where it is very difficult to bring those back online - certainly a very expensive, difficult prospect of ever bringing them back online. So I think this is going to be a very important moment when it's done," he said.

The U.S. team will be working with a North Korean team to carry out the disabling of the Yongbyon reactor and related facilities. Hill says the U.S. experts are set to travel to the site on Sunday. "They'll be going to Yongbyon tomorrow, and by Monday they will begin their work," he said.

The six-party talks began in Beijing in August 2003, among the two Koreas, China, Russia, Japan and the United States. There were long delays and boycotts by North Korea along the way.

In October of last year, Pyongyang announced it had conducted its first nuclear test. While the scientific consensus was that the test was at best only a partial success, scientists seem convinced that it was indeed a nuclear explosion.

The international community reacted with outrage, and levied sanctions against North Korea. Even the North's traditional supporter, China, voted in the United Nations Security Council for sanctions.

But the six-party talks resumed, and in February, an agreement in principle was reached. In return for aid and diplomatic concessions, Pyongyang said it would reveal and disable all of its nuclear programs.

The Yongbyon reactor was shut down in July, and preliminary deliveries of fuel and other aid have been made. Hill says negotiators are expecting North Korea's full list of its nuclear facilities and programs within two weeks, and full disablement is expected to begin early next year.