WBRZ - Baton Rouge

WASHINGTON - U.S. intelligence officials say North Korea's nuclear test yielded an explosion of "approximately several kilotons."

In a statement Tuesday, the Office of the Director of National Intelligence said North Korea "probably conducted an underground nuclear explosion in the vicinity of P'unggye." It said the explosion yield was "approximately several kilotons" and that analysis of the event is continuing.

South Korea's Defense Ministry said it detected an estimated explosive yield of 6-7 kilotons.

President Obama called North Korea's action "highly provocative" and said it threatens U.S. security and international peace.

The test is seen as a crucial step toward Pyongyang's goal of building a bomb small enough to be fitted on a missile capable of striking the United States.