Knowledgeable sources said Tuesday that North Korea has agreed to declare its willingness to dismantle its nuclear weapons program in exchange for a U.S. promise to give it a written, multilateral security assurance.

According to Western diplomatic sources, the North's willingness for de-nuclearization and the U.S. security pledge are to be contained in a joint declaration to be adopted at the end of the six-nation nuclear talks.

The United States relayed to China the idea of reciprocating pledges with the North when U.S. Assistant Secretary of State James Kelly visited Beijing last week.

China, in turn, outlined the U.S. proposal to the North's Vice Foreign Minister Kim Yong-il, when he met Chinese Foreign Minister Li Zhaoxing and other diplomats during his ongoing visit to Beijing.

Kim, who represented the North at the first round of nuclear talks in August, has been in China since Saturday.

The sources also said the United States was to brief Russia on the proposal when Kelly meets Russia's Deputy Foreign Minister Alexander Losyukov in Washington on Tuesday, Korean Time.

No date has been set for a second round of six-way talks, but some South Korean and Japanese media, quoting unidentified sources, have reported that the next meeting will be held from Dec. 17th to the 19th.