20 Years After First Nuclear Test, North Korea Abandons 'Defensive' Doctrine

North Korea has moved away from a defensive nuclear posture toward a more assertive stance that does not rule out a preemptive strike — a major strategic shift since the country conducted its first nuclear test 20 years ago, according to an assessment by a leading U.S. expert on Korean Peninsula affairs.

The assessment comes as North Korea marks 20 years since its first nuclear test, a milestone in the evolution of Pyongyang's military direction.