The Russians are coming. The Russians are coming. Nowwhere does that scare story ring truer than for West European shipowners faced by cut-throat competition from the Soviet merchant navy's incisive incursions into key Common Market ports and strategic.

The Soviet cargo liner fleet "is now the largest in the world," charge officials of the nine-member European Economic Community, which has seen the dominant 40 per cent share of world shipping it enjoyed in 1959 slump of a modest 22 per cent this year. Happiest of Soviet hunting grounds is Western Europe.

A Common Market crackdown against the Soviet-led Eastern Europe Shipping offensive is now being planned here for implementation if the Soviet government does not heed the warning signs. European officials, who have been instructed by worried Common Market ministers to draw up defensive measures, warn of a "general threat to the shipping companies in the EEC" and of possible "eyeball-to-eyeball confrontation.

The strategic implactions of this economic menace are also being "actively studied" at NATO headquarters, according to alliance diplomats here.

The Eastern shipping invasion, which officials here fear will intensify in the next two years, takes the shape of a two-pronged pincer movement striking at the heart of Western Europe's declining shipping industry.

Thrust number one is focused on the major North Sea ports of Antwerp in Belgium, Rotterdam in Holland and Hamurg in West Germany claim EEC officials. A standing joke here is that "Hamburg is the largest Soviet port," a sally of black humor which dramatically emphasizes the immediacy of the Soviet threat.

Thrust number two is seen as aimed at the River Rhine, Western Europe's main inland waterway, which is to be linked by an ambitious canal network to the Soviet-dominated Danube and Black Sea.

Although the Rhine-Danube link is a West German inspiration, European officials fear that this spectacular East-West tie-up could most benefit the Soviets by giving their ultra-competitive fleet a tight grip on the jugular vein of European inland water transportation, as the Rhine is seen here.

The more immediate of the two actions surmise Common Market officials, is the looming Soviet presence in the North Sea, but so far Western Europe's response has lacked cohesion and effect.

"Each for himself and God for all of us, as the elephant said as he danced among the chickens," is the biting assessment made by one EEC transport aide of the U.S.S.R.'s success in resisting separate demarches made earlier this year by Britain, Germany and Belgium.

Faced with this failure, a unified European response is now in the planning stage. EEC countries are currently analyzing joint protectionist action, Denmark, another nation hit by East European pressure, is expected to use its leadership of Common Market affairs during the first half of 1978 to turn the European screw on the Soviets.

Defense measures envisaged by European officials include slapping quotas on Soviet freighter presence in EEC ports, forcing East European cargo freight charges up, and cutting back the number of Soviet shipping agencies established in West European countries.

Major European charges leveled at the U.S.S.R. are its insistence that Soviet ships carry the vast proportion of two-way trade, prices set at 30 per cent below normal market rates, and the "state monopolistic enterprises" which make such practices, seen here as "non-commercial," an economic possibility. The Common Market industry, say market officials, is in a critical situation.

But the Soviets have so far been intractable, scoffing at these complaints. According to European officials, they "have accused Western shipping circles of trying to take advantage of present economic strains to reduce their governments to adopt measures of protectionism in international shipping in order to eliminate unwelcome competitors."

The commercial threat is compounded by a military menace, say European officials. They identify East Europe's "military objective" as requiring "a sufficiently large and appropriately structured socialist merchant marine as a complement to regular military transport equipment."

The military dimension of the problem is being tackled by NATO. A priority concern, say alliance diplomats, is the impact of a possible Soviet stranglehold on Western supplies in a period of military crisis.