As the legal battles over the U.S. Navy's use of active sonar continue to rage, any sign of a truce is welcome.

This was the case Tuesday, when an agreement was announced between the Navy and environmental groups over the use of powerful low-frequency sonar.

The deal is a compromise between two compelling interests: national security and environmental protection.

Both interests must be served. And clearly the best way to do so is through agreements like this, rather than the seemingly endless stream of litigation that has characterized this complex issue.

Low-frequency sonar training is needed, the Navy says, to hone its skills in the long-distance tracking of modern quiet submarines, like those used by Iran, China and North Korea.

But there's no doubt — the Navy's own studies confirm it — that loud sonar blasts can cause permanent injury or death to marine mammals, including those protected under federal law. Recognizing this, federal courts have restricted the Navy's use of active sonar in a patchwork of rulings that have left the issue muddled — and the Bush administration eager to sweep away the confusion by seeking an overreaching exemption.

The new agreement shows the value of a middle path.

It allows the Navy to conduct training with this Low Frequency Active sonar, known as LFA, in defined areas of the North Pacific.

But it bans LFA sonar training within 50 nautical miles of the main Hawaiian islands, and keeps the testing well away from the Hawaiian Islands Humpback Whale Marine Sanctuary and the Papahanaumokuakea Marine National Monument. The agreement also offers protections relating to whale breeding grounds and seasons.

It's not the perfect solution.

LFA sonar can still disrupt whale behavior from more than 300 miles away, even if, as the Navy contends, the effects would be minimal.

And the Navy's mid-frequency sonar continues to be a contentious, unresolved issue. This type of sonar travels shorter distances but can cause greater harm to marine life than LFA sonar, environmentalists say.

The U.S. Supreme Court will hear arguments over the Bush administration's attempt to exempt the Navy from environmental laws restricting the use of mid-frequency sonar off the Southern California coast.

No doubt, the Navy needs to train its sailors to correctly interpret sonar data under realistic conditions, so they can tell the difference between a submarine and a seamount. It could be the difference between life and death, and our nation's security.

But is the Navy confronting a national security emergency that should put its operations above the law of the land, as the administration contends?

Not likely. The correct solution lies somewhere in between, attainable only through negotiation and compromise.

Both issues — environmental protection and national security — are far too important to do anything less.