Diplomats in Geneva say North Korea has allowed United Nations nuclear monitors to return to the country's main nuclear facility after kicking them out last week.
Diplomats say inspectors from the International Atomic Energy Agency have regained access to all facilities at the site, including the plant that produced plutonium for nuclear weapons.
Pyongyang announced Sunday it would resume disabling the Yongbyon facility.
North Korea barred IAEA inspectors from the site last week to pressure the United States to remove if from a terrorism blacklist.
The United States removed North Korea from the blacklist on Saturday, saying Pyongyang had agreed to all of its nuclear inspection demands.
Monday, China praised the efforts of participants in the six-nation talks on ending North Korea's nuclear weapons program, calling them constructive.
Nuclear negotiators say the turnaround will be an opportunity to get the six-party nuclear talks back on track.
On Sunday, North Korea promised to allow U.S. and U.N. nuclear inspectors to verify the dismantling work.
Washington says Pyongyang will allow monitoring of North Korean plutonium and uranium development plans and any nuclear proliferation activities.
The six parties involved in the nuclear disarmament talks are North and South Korea, China, the United States, Japan and Russia.
Some information for this report was provided by AFP.