A federal appeals court has ruled that the U.S. Navy was wrongly allowed to use sonar in the nation's oceans that could harm marine life.
The court reversed a lower court decision which had granted for the Navy in 2012 to use low-frequency sonar for training, testing and routine operations in the oceans.
The five-year approval also covered peacetime operations in the Pacific, Atlantic and Indian Oceans and the Mediterranean Sea.
The matter was sent back to the lower court for further proceedings by the appellate panel.
"We have every reason to believe that the Navy has been deliberate and thoughtful in its plans to follow NMFS guidelines and limit unnecessary harassment and harm to marine mammals," the Guardian quoted the appellate ruling as saying.
Environmental groups, led by the Natural Resources Defense Council in 2012, filed a lawsuit in San Francisco arguing the approval violated the Marine Mammal Protection Act.