INTERVIEW: 20 yrs after 1st nuclear test, N. Korea drops "defensive" doctrine: expert

TOKYO - North Korea has moved away from its defensive nuclear posture to a more assertive one that does not rule out preemptive strikes, a major shift in strategy since it carried out its first nuclear test 20 years ago, according to a leading U.S. expert on Korean Peninsula issues.

Underscoring Pyongyang's determination to be recognized as a nuclear weapons state, Victor Cha of the Center for Strategic and International Studies, who served on the National Security Council in the George W. Bush administration, said North Korea now has 50 to 60 nuclear weapons and enough fissile material to build as many as 100.