"North Korea has revealed to the United States that it has a secret and active nuclear weapons program, an acknowledgment made only after Pyongyang was confronted with evidence that it has enough plutonium for at least two nuclear weapons, senior administration officials said Wednesday.
North Korean officials confirmed U.S. suspicions during this month's high-level U.S. visit to Pyongyang, led by James Kelly, the assistant secretary of state for Asian affairs. "

OK, raise your hand if you hadn't already guessed this.

CNN.com - U.S.: North Korea admits it has nuke program