In contrast to the delicate arms-control minuet the superpowers are dancing in the ornate negotiating halls of Europe, the United States and the Soviet Union are engaged in a brawling struggle for military and diplomatic dominance in the vast reaches of the Pacific.

At stake is the wealthiest and fastest-growing region in the world - a sprawling boom town vital to the economic health of the United States and a tempting source of money and technology for the battered Soviet economy.So decisively are U.S. interests shifting toward Asia that many analysts, such as former Navy secretary James Webb, say the United States' postwar security strategy, heavily oriented toward Europe, is seriously out of whack.

"Our country's interests are moving west and south," Webb declared, but U.S. forces worldwide are "pretty much where the tanks stopped" in 1945.

A new study by the liberal Brookings Institution concurs: while the United States has always considered itself a Pacific power, "the need for an active American presence in the region will grow rather than decline" in the decades ahead.

Both President Bush and Soviet President Mikhail Gorbachev have expressed enthusiasm for the new superpower competition in the Far East, with Bush making his first overseas trip as president to the region later this month and Gorbachev to follow on a summiteering junket later this spring.

But the competition also holds perils, and will require adroit diplomacy in the years ahead.

Seven of the world's largest military powers maintain forces in the region, including nuclear-armed forces of the United States, Soviet Union and China. India has nuclear weapons technology and is fielding aircraft carriers and nuclear-powered submarines.

At the same time, growing nationalism is threatening stability in the Philippines, Korea and elsewhere.

But the key confrontation is between U.S. and Soviet forces in the Pacific, which are positioning themselves to intervene in crises and to play a central role in any global war.

"Militarization and the escalation of the threat of war in this part of the world is picking up dangerous speed," Gorbachev warned in a speech at Vladivostok two years ago, adding: "This is alarming."

In Asia, the United States and the Soviet Union have not engaged in the kind of military-to-military talks and observation of each others' military exercises that have become common tension-relievers in Europe, Pentagon officials said.

Instead, the two superpowers are beefing up their naval and air forces and jostling each other in increasingly aggressive combat exercises and "presence" missions.

Since 1985, the Soviets have reduced the size of their Pacific fleet but have replaced most of their aging ships with modern, more capable surface warships and submarines, and deployed dozens of bombers armed with cruise missiles designed to strike U.S. ships and shore facilities.

The United States has also increased and modernized its Pacific forces, adding F-16 fighters in Korea and Japan, creating a new carrier task force and two battleship task forces, and deploying attack submarines, ballistic missile submarines and surface ships armed with Tomahawk cruise missiles.

Operationally, the Soviet Pacific fleet has more than doubled its blue-water patrols since 1975, and recently began joint combat operations with North Korea.

The U.S. Navy began in 1983 to patrol the Sea of Okhotsk, adjacent to the Soviets' ballistic missile submarine bastions, with attack submarines and anti-submarine aircraft, which practice offensive operations as part of their "presence" mission.

The aggressive U.S. strategy was condemned recently by the top Soviet naval officer, Adm. Vladimir Nikolayevich Chernavin, who complained that U.S. operations in the Pacific are dangerously provocative.

The U.S. reaction: "You just can't get enough fan mail like that," in the words of Adm. David E. Jeremiah, commander in chief of the U.S. Pacific Fleet.

In one exercise that took U.S. aircraft carriers within 50 miles of the Soviet coast, the Soviets responded with more than 100 fighter, bomber and reconnaissance flights over the U.S. warships, according to an analysis of U.S.-Soviet clashes in the Pacific by William Arkin of the private Institute for Policy Studies.

In a rare publicized event, the U.S. carrier Kitty Hawk collided with a Soviet attack submarine, and a few weeks later a Soviet pocket carrier fired flares at an American frigate to warn it to stand clear.

Former Navy secretary John Lehman said about 40 such "potentially dangerous" incidents occurred in 1982 and there is no evidence, Arkin reported, that that rate has declined.