North Korea recently announced that it has manufactured nuclear weapons for self-defense and is suspending participation in disarmament talks.
"This is a long-standing problem. It's a latest twist in a complicated story. It's a problem which will have to be tackled by the parties of the six-party talks. I'm sure the Americans, the Chinese, the Russians, the Japanese, the Koreans -- they are busily caucusing to decide what is the best way to deal with this very prickly problem, which worries all of them," Lee said.