The Defense Agency may simplify the procedures under which the prime minister can order countermeasures in the event of a ballistic missile attack on Japan, it was learned Tuesday.

Under the plan, the prime minister would be able to authorize countermeasures on the basis of Cabinet approval alone, sources said. The Diet would then be asked to endorse a given maneuver after it is carried out.

The move is viewed as one potential modification of Japan's legal framework in preparation for the introduction of a missile defense system, observers said.