Basically, Colin Powell, our Secretary of State, went on a three country tour of Asia discussing the North Korean issue and stated that it would be "wise" of North Korea not to restart their nuclear reactor in Pyongyang.
Unfortunately, North Korea thought he said restart the reactor, so they went ahead and did it.
This is only a report, though, and has yet to be confirmed.
South Korean Prime Minister Goh Kun said he was unable to confirm the report but will "resolve the issue peacefully... in close cooperation with the United States."