The US Navy has been temporarily banned from using sonar. A federal judge in California slapped a restraining order on the military after environmentalist lawyers successfully argued that marine mammals could be at risk.
The Navy had this week planned to carry out its anti-submarine training exercise, called Rim of the Pacific (Rimpac) 2006, involving 40 ships, six submarines and plenty of high powered sonar equipment.
It had been granted a special six month exemption from the Marine Mammal Protection Act by the government, specifically to carry out training exercises involving sonar.
However, the judge's ruling was instead based on the National Environmental Policy Act.
In her ruling, district court judge Florence-Marie Cooper said that she accepted the plaintiff's argument that proposed military training exercises could "kill, injure, and disturb many marine species, including marine mammals, in waters surrounding the Hawaiian Islands", the BBC reports.
The US government's lawyers are reviewing the ruling, and will have an opportunity to argue for the injunction to be lifted at a full hearing on 18 July. ®