North Korea has reversed steps to restart its Yongbyon nuclear reactor, the U.S. State Department reported Friday, making good on a pledge to resume disabling its major nuclear facilities after the United States removed the nation from its list of state sponsors of terrorism.

State Department spokesman Sean McCormack told reporters in his daily briefing that the seals are back on the reactor, and that the North Koreans have removed 60 percent of the reactor rods from the facility.

He told reporters that puts them "beyond where they were prior to their reversing the disablement."

U.S. and International Atomic Energy Agency officials are already on the ground, officials say.

"There is still work to be done" at reprocessing and fuel fabrication factories, McCormack said. But he added that he expected nuclear talks among China, Japan, the two Koreas, Russia and the United States to resume "in the coming period of time." He would not discuss specifics because host China has announced the meeting.

The progress at the Yongbyon plutonium reprocessing plant came after North Korea ended a two-month boycott of a six-nation nuclear disarmament deal following the United States' removal of the country from a terrorism blacklist as an incentive.

On Tuesday, the North let U.N. monitors back into the nuclear site. A diplomat in Vienna familiar with the International Atomic Energy Agency's work in the North said the agency's three-member team had resumed monitoring Tuesday.

Six-nation nuclear talks took on new urgency after North Korea set off a test nuclear blast in 2006. It then agreed to dismantle its nuclear program in exchange for energy aid and other concessions, though negotiations have since been beset by deadlock and acrimony.

North Korea halted its nuclear disablement in mid-August in anger over what it called U.S. delays in removing it from the terror list and began moves toward restarting its plutonium-producing facility.

The U.S. said over the weekend that it took the country off the terrorism blacklist because it had agreed to all U.S. nuclear inspection demands.

The Associated Press contributed to this report.