With their highly trained crews, the 33 fast attack submarines of the U.S. Pacific Fleet constantly practice to be silently in place when needed.

The fast-attack submarine USS Charlotte slipped quietly through the narrow channel out of this famed naval station [Pearl Harbor]. It quickly reached the 100-fathom mark, and dived under the gentle roll of the Pacific to head west on patrol along the coast of Asia.

 The crew wouldn’t say where they were going or when they would be back, but their conversation left little doubt that they would be cruising the shallow waters off North Korea or China or in the well-traveled shipping lanes of the South China Sea. The adversary of five years ago, the once-powerful but now rusting fleet of the Soviet Union, was not on their minds.

 Since the end of the Cold War, the mission for Charlotte and 32 other fast-attack submarines in the Pacific fleet has fundamentally changed. Today, they are responding with new weapons, tactics and technology to the rise of military powers in Asia, many of which have submarines, and the proliferation of nuclear and other weapons of mass destruction. The same is true for a similar fleet in the Atlantic that was earlier even more targeted on the Soviet threat.

 The change has laid new tasks on the Pacific submarine force base here [in Hawaii] and San Diego. "We’re operating at the same tempo we did five years ago" said a submarine officer "but we have a lot of new missions and fewer boats because the Navy is being downsized. So we’re gone from home port about 50 percent of the time."

 Before, American fast-attack submarines hunted alone through deep water for nuclear-powered Soviet submarines loaded with nuclear-tipped ballistic missiles aimed at Washington, New York, Los Angeles and U.S. nuclear missiles and air bases. Armed primarily with torpedoes, they searched for Soviet submarines that might threaten U.S. warships, tankers or cargo ships.

 Today, Charlotte prowls tricky shallow waters above continental shelves as it hunts for diesel-electric submarines of Third World navies, collects electronic and visual intelligence, and scouts for potential sites in which to lay mines. Its crew trains to put ashore commandos, fire anti-aircraft missiles from below the surface and operate via advanced communications with surface ships, army troops ashore and air force planes overhead.

 In the Pacific Command’s area of operations, which extends from the West Coast across the Pacific and Indian Ocean to the East African coast, 10 nations have submarines powered by diesel-electric engines. They include North Korea, South Korea, Japan, Taiwan, Indonesia, Australia, India, Pakistan, and South Africa; China has [also] begun building a nuclear-powered submarine fleet.

 For U.S. submarines, operating in shallow water requires fresh training for crews experienced in cruising in deep water in boats that can dive much deeper than the 800 feet to which the Navy admits and can run much faster than the 25 knots it acknowledges.

 In shallow water, if it is clear, a submarine can be seen from the air. Navigation is nerve-wracking because of islands, reefs, seamounts and narrow channels or choke points. Warm, swirling water often plays havoc with the sonar on which the crew depends to know where they are, to find targets and to evade adversaries. Some training for such operations is conducted over Penguin Bank, off Oahu’s Koko Head.

 A submariner aboard Charlotte talks about the difficulty of operations in shallow-water areas, among the most treacherous of which is the South China Sea amidst the Philippine and Indonesian archipelagos and the Indonesian and Malaysian peninsula.

 He shakes his head and his voice trails off as he mutters, "The South China Sea..." Perhaps most important, Charlotte’s 12 cruise missiles carried in vertical tubes in its bow have come into their own. Armed with conventional, not nuclear, warheads to attack targets deep in the interior of an adversary, these flying torpedoes can hit a target from 700 miles away with the enemy unable to determine from whence they came.

 During the war around the Persian Gulf in 1991, a U.S. submarine fired earlier versions of the cruise missile from the Red Sea across Saudi Arabia to strike targets in Iraq. Once it popped out of the sea, the missile’s turbofan engine ignited and stubby wings snapped into place. The missile found land with inertial navigation, then had sensors compare the terrain with a map stored in a computer to make corrections. Closer to the objective, radar searched out the precise target, and guided the missile in.

 Charlotte and other nuclear-powered boats have also acquired a new mission in deterrence. The silent service, as submariners like to call themselves, is still silent about secret technology, tactics and precise areas of operation, but more open about submarine presence and capabilities.

 "We are often the first on the scene," said an officer in Charlotte, "because we’ve been positioned where trouble has been anticipated. We can go eyeball a situation and no one knows we’re there."

 Then, if it would serve to deter, the presence of the submarine can be made public. A year ago, the United States let it be known that four submarines were operating off the coast of China, along with two aircraft carriers and other surface warships, in response to Chinese military threats to Taiwan. Two subs were integrated into the carrier battle groups while two were operated independently, guarding the exits to the Taiwan strait and monitoring Chinese naval bases. No Chinese warship could have put to sea without a U.S. submarine knowing about it.

 The new roles for fast-attack submarines are part of the "revolution in military affairs" in which more emphasis is placed on high-tech intelligence-gathering, swift and secure communications, computer-driven decisions, speed in execution and stealth, and less on manpower, to carry the brunt of the attack. The fast-attack submarine, with a crew of only 130, is at the heart of that leaner, meaner force.

 Even so, some things never change, chief among them the need for men who can master the high technology and whose instincts are good. A petty officer stood behind Charlotte’s navigation plot and waved his hand at the advanced apparatus with which the blind boat operates in the depths of the sea. "If my guts tell me something isn’t right," he said, "nine times out of 10, it isn’t right."

 In the torpedo room, a chief petty officer says the addition of the cruise missiles gives his crew more to do even if the technology and training are related to operating the torpedo tubes. "The mind-set is the same," he says. "but we didn’t get any more people, we just have more to do."

 Another chief petty officer says the young men – women do not serve in cramped submarines where there is little privacy – absorb technical training well. He points out one shortcoming: "These kids are used to playing computer games, which is good for technical skills. But if they’re not winning, they just hit the ‘delete’ key and start over. Life is not like that, especially on a submarine. You can’t hit ‘delete’ and walk away."