The chairman of the U.S. Joint Chiefs of Staff has expressed concern over the possibility of North Korea conducting another nuclear test.

Admiral Michael Mullen said at a forum in Washington Tuesday that there are reports of Pyongyang considering additional testing of nuclear weapons. He did not confirm nor deny these reports, but did say the reports are worrisome because the North is armed with nuclear weapons.

The U.S. State Department says it has never recognized the North as a nuclear state and has no plans to do so in the future.

Mullen also called for active U.S. intervention so that the North will drop its belligerent position.

The North first tested a nuclear weapon in 2006.