A team of American experts returned Thursday from talks in North Korea on disabling the regime's main nuclear reactor.
The group, led by Sung Kim, the U.S. State Department's top Korea expert, spent a week in Pyongyang trying to finalize details on the scope and process of disablement.
He arrived at Beijing's airport but did not make any comments. Kim later flew to Seoul to brief South Korean officials on his trip.
The visit follows a meeting of the two Koreas, the U.S., China, Russia and Japan in late September in Beijing, at which North Korea agreed to disable its Yongbyon complex and declare all its nuclear programs by the end of this year.
In return, the North has been promised economic aid and political concessions from the U.S. and the other countries.
Sung's team of technical experts was to put in place a plan for the disablement of Yongbyon's three main facilities. After that, other teams would then go to North Korea to carry out those technical steps.
The Yongbyon nuclear complex is believed to have produced enough plutonium for perhaps more than a dozen bombs - including the device North Korea detonated a year ago to prove its long-suspected nuclear capability.