Beijing: Joint talks on North Korea's nuclear disarmament opened up in an optimistic mood on Wednesday after Pyongyang close down all its five nuclear plants and expressed enthusiasm to come clean on its divisive atomic programme in the coming six months.

Chun Yung Woo, chief negotiator of South Korea said, “North Korea has demonstrated its willingness to disable its nuclear facilities and declare all its nuclear programmes in five to six months.”

U.S. National Security Advisor Stephen Hadley said it seems the North Korean have indeed close down their major plutonium reprocessing facility at Yongbyon, about 100 km north of Pyongyang.