In issuing a deliberately narrow ruling yesterday in a controversial case involving whales and the U.S. Navy, the Supreme Court strongly indicated that it intends to defer to the military in future disputes pitting national security against environmental concerns. The justices voted 6 to 3 to lift restrictions on the Navy's use of sonar off the Southern California coast, backing the military in a longstanding battle over whether anti-submarine training harms marine mammals. Environmentalists say the exercises disrupt habitats and leave the mammals with permanent hearing loss and decompression sickness. But the Navy argued that the training missions are essential to detecting a new generation of quiet" submarines deployed by China, North Korea and other potential adversaries. "We do not discount the importance of plaintiffs' ecological, scientific, and recreational interests in marine mammals," Chief Justice John G. Roberts Jr. wrote in the first decision of the court's current term. "Those interests, however, are plainly outweighed by the Navy's need to conduct realistic training exercises to ensure that it is able to neutralize the threat posed by enemy submarines." Although the majority tailored its decision on narrow legal grounds and indicated that future environmental disputes will be decided on a case-by-case basis, the court made sweeping statements of deference to military judgments. Roberts unquestioningly accepted the assertion of top Navy officers that the exercises "are of utmost importance to the Navy and the Nation," writing that "the proper determination of where the public interest lies does not strike us as a close question."