The Argentine is ruled by a right-wing military dictatorship.
When the Reagan administration in Washington was casting around for ways and means of damaging and perhaps even bringing down the leftist revolutionary government in Nicaragua it approached the members of the ruling junta in the Argentine. A tentative plan was worked out for Argentine ''volunteers'' to undertake a ''destabilizing'' operation in Nicaragua.
The plan was based on the assumption that since the Argentine junta presides over a capitalistic economic system and is vigorously ''anticommunist'' in its domestic policies, it would be happy to cooperate with the United States in any operation aimed at reducing both communism and Soviet influence in Central America.
There is no room for doubt about Argentine anticommunism at home. Thousands of persons of communist or suspected communist sympathies have ''disappeared'' during what amounted to a civil war. Political communism is not tolerated in the Argentine itself.
But who, when the Soviet Union invaded Afghanistan and President Carter imposed an embargo on the sale of US grain beyond the contractual US commitment, gladly sold its own grain to the Soviets to make up for the American grain they could not get?
The Argentine had no compunctions about undercutting the US attempt to penalize the Soviets. In fact one fallout from the grain embargo story has been a reorganization of the grain flow in world markets.
In the pre-Afghanistan era the US used to ship somewhere around 15 to 18 million tons of grain a year to the Soviets. This current year the US is offering 23 million tons, but the Soviets have only signed contracts for about 12.5 million tons. Shipments so far are half of the total under contract.
Meanwhile, the Argentines have greatly expanded their grain export port facilities. In August 1980 they signed a five-year agreement with the Soviets to sell them 4.5 million tons per year and make available another 10 million tons. In 1981 they supplemented the grain deal with a contract to sell the Soviets 60, 000 to 100,000 tons of boneless beef. During the previous year, 1980, they shipped 90,000 tons of Argentine beef to the Soviets. That was well above any previous rate of sale of Argentine beef to the Soviets.
The present US contract for grain sales to the Soviets runs out in September. The Soviets seem in no hurry to enter into a new agreement. The Argentine is taking over a substantial share of the grain market which the US once enjoyed in the Soviet Union.
The Soviet Union is the automatic beneficiary of the Argentine invasion of the British Falkland Islands. That invasion forced on the British government the dispatch of two thirds of the British Royal Navy (complete with a prince of the royal blood aboard) to the South Pacific.
This subtracted the Royal Navy from the NATO order of battle in European waters. This put an increasing burden of deterrence activity on other NATO navies, including the United States Navy.
And what important foreign government was the first to give verbal and propaganda encouragement to the Argentine?
The Soviets have denounced the British effort to regain the Falkland Islands as being ''colonialism.'' They disappointed the Argentines by not using their veto against a motion of censure in the UN Security Council. But they did abstain. And in their propaganda they assume that the Argentine has a case for seizing the islands from British rule.
In other words, Moscow does not play world politics ideologically. It has no compunctions about buying grain and beef from a government which is frequently and probably justifiably called fascist. Nor do the Argentine leaders have compunctions about taking over US markets. They do not object to Moscow's money. Nor are they concerned over the fact that their invasion of the Falklands has subtracted the British Navy from NATO's order of battle in Europe.
As of today Argentina is a more useful vehicle for Soviet influence in Latin America than are Cuba, Nicaragua, and the rebels in El Salvador.