The Navy said yesterday it won't tell a federal court specifics about its use of sonar over the past four years because disclosing such information would jeopardize national security.

A U.S. District Court judge in Los Angeles had asked the Navy to submit data for when and where sailors have used sonar since 2003. Judge Florence-Marie Cooper issued the order in response to a request from the Natural Resources Defense Council, which is suing the Navy to ensure sailors use sonar in a way that doesn't harm whales and other marine mammals.

Cooper instructed the Navy to list the latitude and longitude of where it used midfrequency active sonar, how long it used the sonar, and the times and dates of each instance.

Navy officials are worried such detail could give potential enemies critical tactical information about how sailors employ sonar to track and target submarines. Citing state secrets privilege, which allows government officials to keep information secret on national security grounds, the Navy said it wouldn't release the data.

"If you look at it in the aggregate, it paints a picture that we wouldn't want to paint for our adversaries," said a Navy official who asked not to be identified because the matter was still being litigated. "It was imperative for the Navy to assert this state secrets privilege in order to protect our national security interests."

Joel Reynolds, a Natural Resources Defense Council attorney, said he would challenge the Navy's position.

The Navy should have no problem releasing the information because it wouldn't cover any use of sonar in combat or in "heightened threat" circumstances, Reynolds said.

Further, the council and the court needs the data to ascertain how the Navy has complied with environmental laws when sailors use sonar.

"This latest invocation of state secret privilege is one more attempt to deprive the public of the information it needs to determine whether the Navy is illegally and needlessly endangering the marine environment," Reynolds said.

Critics say active sonar, which sailors use by pumping sound through water and listening for what objects the sound bounces off of, can strand, injure and even kill whales and marine mammals.

Environmentalists say sonar can interfere with the ability of marine mammals to navigate, hunt, take care of their offspring and avoid predators.

The Navy acknowledges sonar may harm marine mammals but says it already takes steps, such as posting lookouts, to protect whales.

It also says more study needs to be done before sailors adopt restrictions on training demanded by the Natural Resources Defense Council and other environmentalists.

Navy officials say many factors cause marine mammals to become stranded, including pollution, disease, starvation and collisions with ships.

Sonar training has become increasingly important to the Navy in recent years as more countries, including China and Iran, have been acquiring sophisticated quiet submarines that are harder to detect.

The Pacific Fleet's commander made anti-submarine warfare training his sailors' highest war-fighting priority in 2005.

The confrontation over state secrets privilege is only the latest flare up between environmentalists and the Navy over sonar.

Last month, the Navy rejected the California Coastal Commission's attempt to regulate the Navy's use of sonar in federal waters off California.

The Navy said the commission had jurisdiction only over state waters.

In July, the council and the Navy fought over whether the Navy could use sonar during large-scale international exercises off Hawai'i. The war games went ahead, but a federal judge ordered the Navy to increase its lookouts for marine mammals during the drills.