LOS ANGELES (AP) — A federal judge ordered the Navy on Thursday to adopt measures that would lessen the impact of sonar on whales and other marine life during exercises near Southern California.

The preliminary injunction issued Thursday requires the Navy to create a 12-nautical-mile no-sonar zone along the coast and have trained lookouts watch for marine mammals before and during exercises. Sonar should be shut down when mammals are spotted within 2,200 yards.

Cmdr. Jeff Davis said the Navy does not believe the ruling "struck the right balance between national security and environmental concerns."