Diplomatic sources said Friday that North Korea will blow up the cooling tower at its Yongbyon nuclear facility once the United States takes steps to remove the North from its terrorism blacklist.

According to the sources in Seoul and Washington, the decision is in line with a North Korean pledge that it would destroy a key facility as a symbolic gesture. This would reaffirm its will to begin second-stage denuclearization.

The United States and other Western countries have been monitoring the North's nuclear activities and have photographed vapor coming out of the Yongbyon cooling tower.

The sources said North Korea has also agreed to declare all operations at the Yongbyon nuclear reactor.