Today, the United States and the Soviet Union are emphasizing naval forces and maritime strategy as key elements in their quest for military predominance in the world.
Briefings for President Reagan this week in Hawaii on the Soviet threat in the Pacific; ongoing naval exercises in which US and Soviet ships shadow and sometimes nudge each other; and the steady buildup in size and sophistication of both fleets illustrate this.
Under Adm. Sergei G. Gorshkov, commander in chief of the Soviet fleet for nearly three decades, Soviet sea power has evolved from a coastal defense force to a ''blue-water navy'' designed to extend throughout the world's oceans. Since late last year, a series of naval exercises has been held in the Indian Ocean, South China Sea, and the North Atlantic, emphasizing operations against aircraft carriers and submarines, and to block sea lanes. Most recently, a Soviet surface-action group headed by the helicopter carrier Leningrad and a large cruiser has been operating in the Caribbean.
Soviet and Warsaw Pact naval forces do not yet match those of NATO. According to Western intelligence sources, there are 1,400 ships in the East-bloc fleet, compared to 1,500 in the West's (1,700 with those of non-NATO France and Spain included). And NATO has an even greater lead in major war vessels of more than 1 ,000 tons displacement.
But the Soviet fleet has been catching up. And in many ways, it now is emulating the US fleet in an effort to achieve greater power projection capabilities. The Soviets are building their first large nuclear-powered aircraft carrier to launch and recover fighter jets. They are launching more ballistic-missile submarines to restructure a strategic arsenal that currently emphasizes vulnerable, land-based, intercontinental ballistic missiles.
This past year, two new classes of Soviet nuclear-powered attack subs were begun as well. And they are stressing advanced cruise missiles launched against sea and land targets from submerged and surface ships.
In recent months, the Soviet Union has also continued to expand its naval support facilities at Cam Ranh Bay, Vietnam, and in the Dahlak Archipelago in the southern Red Sea off Ethiopa. These now include long-range naval strike aircraft and units of the Soviet naval infantry (marines).
The US Navy, under President Reagan and Navy Secretary John F. Lehman Jr., has become the more active and most obviously bristling military service as well.
With construction completions, and keels layed, the controversial 600-ship navy has become fact. In the push for two new aircraft carrier battle groups and more battleships, the emphasis continues to be on power projection and influence abroad. Another refurbished battleship, the USS Iowa, will be recommissioned Saturday, eventually to be armed with nuclear-tipped cruise missiles as well as its mammoth 16-inch guns.
Recent exercises in the North Atlantic and Caribbean show the ambition with which the US plans to protect its home turf and thrust into Soviet waters if necessary. Yet another exercise involving 350 ships and 30,000 personnel at a cost of $25 million began last weekend.
But even among US defense officials, support for Mr. Lehman's push for maritime superiority is not unanimous. Defense Undersecretary Richard D. DeLauer and former deputy defense secretary Paul W. Thayer have questioned the emphasis on carriers and other large surface ships that could make lucrative targets.
In a recent secret memo, Adm. James D. Watkins, chief of naval operations, reportedly warned that the US fleet is suffering a ''serious shortfall'' in advanced missiles and other weapons.
One senior officer, asked to critique the Navy's latest strategy outline, grumbled about the ''widespread use of overly simplistic assumptions.''
Yet both superpowers are intent on countering what they see as their opponent's increasing naval might.
''A primary Soviet objective is naval interdiction of the lifelines connecting the United States, its allies, and the West's sources of vital fuel and minerals - 95 percent of which move by sea,'' Secretary Lehman wrote recently. ''Their target, therefore, is not only or even primarily our warships, but rather our supply ships, our Army sealift, and our merchant vessels.''
The Soviet Union now has eight types of submarines in production, some featuring titanium hulls, providing better survivability and the ability to operate at greater depths. This is a counter to the US edge in anti-submarine warfare capabilities and NATO's very long supply line from the United States to Europe.
The recent Soviet naval exercise in the Norwegian Sea and North Atlantic - the largest such Soviet exercise ever held - tested the Soviet Navy's ability to break out of its home water and take the offensive at sea.
US strategy in the event of general war is to bottle up the Soviet fleet and attack missile-bearing submarines in port.