HONOLULU -- An environmental group's lawsuit against the Navy's use of sonar in Hawaiian waters is now before a federal judge.

A ruling is expected soon, and the Navy wants to use the sonar in training exercises next month.

The U.S. Navy uses sonar to detect submarines and during training exercises.

Environmentalists contend the noise from sonar is harmful to marine mammals, such as whales, and that the Navy is not doing enough to address that.

"We're not saying 'don't train.' We're just saying you need to do a better job of safeguarding the environment," Earthjustice attorney Paul Achitoff said.

The Navy said that it is doing enough to make sure harm is not being done while allowing the military to conduct needed exercises.

"Our 29 mitigation measures, or what I would call protective measures, we utilize, allow us to protect the marine mammals and also conduct realistic training," Pacific Fleet Operations Director Capt. Bruce Stewart said.

Last week, another federal judge ruled that the Navy had to observe a sonar free zone off the Southern California coast for exercises there. The Navy is arguing that these exercises in Hawaiian Waters are different from the ones in Southern California.

Environmentalists said even if the exercises are different the Navy's current safeguards to protect marine life from sonar are not enough.

"You're not going to see many whales with binoculars, particularly when in windy conditions, particularly in the middle of the night, even if you use infrared binoculars," Achitoff said.

Federal Judge David Ezra is expected to make a ruling soon since the Navy plans to hold exercises at the end of next month.