A senior U.S. envoy who spent this weekend in North Korea says authorities there are cooperating in the process of disabling the country's nuclear facilities. As VOA's Kurt Achin reports from Seoul, the shutdown is part of a wider diplomatic process aimed at ending Pyongyang's nuclear weapons capabilities for good.

Senior State Department envoy Sung Kim, who oversaw the start of North Korea's disabling of several major nuclear facilities, said the process is going well.

Kim was speaking in Seoul on Tuesday after leading a team of U.S. experts to the North to supervise the process. He says so far, so good.

"I think we are off to a good start," he said. "I hope to achieve all the disablement, at least this phase of disablement, by December 31."

Kim says his team had supervised disabling activities at Yongbyon and several other facilities.

North Korea tested its first nuclear weapon in October of last year, in defiance of international agreements and warnings from the global community.

Since then, however, North Korea has taken first steps in implementing a multinational diplomatic framework aimed at ending its nuclear weapons.

Earlier this year, Pyongyang halted operations at its main nuclear plant in Yongbyon in exchange for energy aid, as it had promised in talks with China, Japan, Russia, South Korea, and the United States.

Diplomats describe "disabling" as a process that would make any restarting of nuclear activity very costly and time-consuming. They say it is a prelude to dismantling the facilities altogether -- a task expected to be discussed sometime next year.

Kim describes North Korean officials as "very cooperative", but says he did not receive any details of the North's planned nuclear declaration.

The second phase of the six-nation agreement offers impoverished North Korea even more energy assistance if it declares all of its nuclear facilities and then substantially disables them.

China is expected to convene another round of six-nation talks in Beijing soon to review the North's declaration.

North Korea has much to gain from ending its nuclear programs including normalized relations with U.S.

A state department spokesman confirmed Washington has begun the lengthy process of removing North Korea from the list of states defined as sponsoring terrorism, a possible prelude to better relations with Pyongyang.