A US appeals court has restored a ban on the U.S. Navy's use of submarine -hunting sonar in upcoming training missions off Southern California until it adopts better safeguards for whales, dolphins and other marine mammals. The order allows the Navy to continue its current exercises, but will force the Pentagon to devise ways to ensure that marine mammals are not harassed or injured by powerful sonic blasts during a series of training missions slated to begin in January.

Those precautions, such as reducing sonar power at night, when whales are not easily spotted, will have to be approved by the same court in Los Angeles that ordered the initial sonar ban in August. The mid-frequency, active sonar has the potential to fatally injure whales and dolphins and the Navy should have no alternative but to increase the level of protection for marine life.

Powerful anti-submarine sonars is carried by Arleigh Burke-class destroyers such as the Shoup.