Los Angeles -- A federal judge issued a temporary restraining order Monday barring the Navy from using a particular kind of sonar allegedly harmful to marine mammals during a Pacific warfare exercise scheduled to begin this week. The order comes three days after the Navy obtained a six-month national defense exemption from the Defense Department allowing it to use "mid-frequency active sonar." Environmental groups had sued to stop the Navy's use of the sonar in the Rim of the Pacific 2006 exercise off Hawaii. The use of sonar in the war games was set to start Thursday. U.S. District Judge...