If Greece extends its territorial waters from 6 to 12 nautical miles, the Soviet Union's naval forces could be left high and dry. But it appears unlikely the Greek Socialist government will force the USSR to abandon its major anchorage at Kythera, 91/2 miles off the Greek coast. Closing the strategically important anchorage could foil the strong Soviet challenge to United States naval dominance of the Mediterranean.
The Soviet Union recently made it clear that it would be strongly opposed to such an extension of territorial waters. Turkey has even threatened war if Greece makes use of its internationally legal right to extend its sea limit. The issue has upset the conservative opposition and press, and has been taken up in the Greek Parliament.
This comes at a time when Prime Minister Andreas Papandreou's Socialist government - partly to appease the left wing of his party and the hard-line Greek communists - met with Soviet Premier Nikolai Tikhonov here in February. The visit - the first ever for a Soviet leader - signaled an attempt to improve relations with the Soviet bloc.
Mr. Tikhonov's visit has resulted in a 10-year agreement for economic cooperation, including provisions for the construction of a natural gas pipeline linking Greece with the USSR through Bulgaria. The Soviets have also agreed to expand trade between the two countries from 400 million rubles ($570 million) to 1 billion rubles ($1.4 billion) per year and to set up a 600,000-ton alumina plant in northern Greece.
It is considerations like these that have led the conservative opposition to believe that, even if the government employs its legal right to expand its territorial waters from 6 to 12 nautical miles, special provision would be made to ensure the Soviet anchorage at Kythera would not be affected.
In Parliament, a recent motion presented by five conservative deputies asked the government whether it had agreed during the Soviet premier's visit to leave Kythera unaffected if it extended its territorial limit. And the Greek press reported that Tikhonov raised the issue of the Kythera anchorage with the Papandreou government.
The results of this reported consultation have not officially been disclosed, and the government has not yet committed itself publicly either way.
The Aegean Sea is of vital importance to the Soviets as a passageway for their ships sailing between the Black Sea and the Mediterranean. Controversy erupted recently over reports that Soviet Foreign Minister Andrei Gromyko, in recent talks with his Turkish counterpart Ilter Turkmen, said his country supported the principle of equite or ''equal basis'' in the Aegean, something that Turkey has demanded since 1974 but Athens has consistently rejected.
The Greeks see such a move as an attempt to stop them from enforcing their legal right under international law to a 12-mile territorial limit around their shores. The same law specifies that islands also have continental shelves, which again favors the Greek position in the Aegean.
Soviet objections are easy to understand. Their anchorage off the island of Kythera, between the southeast tip of Peloponnesus and northwest Crete, is situated in two shallow-water locations around uninhabited and barren islets. For the time being, they are in international waters. Around Kythera the depth of the Aegean slides steeply to well over 100 fathoms (600 feet).
At present, Soviet warships and supply vessels passing through the Aegean on routine missions anchor just outside the six-mile Greek territorial limit. The Soviet Union's lack of bases in this area increases the importance of the Kythera anchorage as a supply, repair, and linkup spot year-round. It receives regular supplies of food, water, and fuel from both its own fleet and Greek contractors, such as the Mamidakis Oil Refinery of Crete.
While minor repairs to Soviet warships are dealt with at the Kythera anchorage, Soviet auxiliary vessels also regularly undergo major repair work at the British-run but Greek-owned Neorion shipyards, on the Aegean island of Syros.
The Soviet Black Sea fleet, part of which operates permanently in the eastern Mediterranean, outnumbers the US Sixth Fleet by 4 to 1 in nuclear submarines and major surface combatants. In addition, the Soviets are the only power in the area with helicopter carriers for antisubmarine warfare.
Yet Washington still maintains an edge over the Kremlin by way of its key military installations on Crete, in Athens, and at Nea Makri, all in NATO-member Greece. Because the Soviets lost their important submarine base at Vlone, Albania, in the 1960s, and other military facilities in Egypt in the 1970s, Kythera has even greater strategic importance for both East and West.
For the Soviets, the need for a naval presence in this area is not a new phenomenon. As a senior Greek naval officer pointed out, ''Russia was formulating policies in the Balkans long before America was even a state.''
Russian control over the Black Sea, and its strong military presence in the eastern Mediterranean, was established in 1770, after a Russian fleet destroyed a Turkish squadron twice its size at Cesme, Turkey. But the lessons of the past have stimulated the Soviets to pursue an expansionist naval policy in the eastern Mediterranean today. Soviet Navy Commander in Chief Sergei G. Gorshkov, in his recent book on Soviet sea power, argues that only a modern, powerful Soviet Navy can overcome the combined forces of all potentially hostile powers in the Mediterranean.
Although the northern seas were of primary importance to Moscow's military planners in the past, the focus of attention has shifted southward. Kremlinologist Michael McGuire notes that the ''eastern Mediterranean is now of greater defensive concern to the Soviet Union than her Arctic seas.''
Even the communist Chinese have criticized Soviet naval expansion in the eastern Mediterranean, warning that the Soviet Union is attempting to ''Finlandize'' Europe by surrounding it with its fleet via the Mediterranean and the Arctic Sea.
To the Soviets, however, criticism from both East and West is water off a duck's back. As a Soviet official here recently said: ''For us, the case is simple. The Aegean must remain a free sea.''