Buenos Aires — The crisis over the Falkland Islands appears to have opened doors to the Soviet Union in this South American country that were not open before.
Because of the diplomatic isolation that was brought on by its invasion of the islands, Argentina is casting about for friends wherever it can find them.
After an initial period of hesitation, the Soviet Union is clearly tilting against Britain in the crisis and in favor of Argentina. As Argentina's leading trade partner, the Soviets are already in a strong economic position here. They recently signed a major fishing agreement with the Argentines.
According to one source, meanwhile, Soviet fishing trawlers are ''all over the place'' on the southern coast of Argentina.
Such trawlers have traditionally been used for electronic spying and for the support of Soviet submarines. It is assumed that the Soviets have a number of submarines operating in this region.
The Argentines seem to have misjudged the international reaction to their April 2 invasion of the Falklands, known here as the Malvinas.
They apparently counted on a more supportive reaction from the United States after President Reagan failed in an attempt to persuade Argentina's President Leopoldo Fortunato Galtieri not to launch the invasion. The US voted against Argentina in the United Nations Security Council and called for an Argentine withdrawal. The Argentine junta was said to have been ''stunned'' by the UN vote.
Latin American nations and other third-world countries also have been less supportive than the Argentines would have liked.
The reaction of the European Community, which imposed economic sanctions against Argentina, was stronger than many here had expected it to be.
The Argentines had hoped for a Soviet veto of the Security Council resolution against their invasion, but the Soviets surprised them by abstaining. Since then , the Soviets have grown more helpful. On April 11, the Soviet Communist Party daily Pravda said that British attempts to regain control of the Falkland Islands by the use of force were inadmissible and contradicted United Nations' rulings on decolonization. Pravda also asserted that US Secretary of State Alexander M. Haig Jr. was acting as a ''messenger for British neocolonialists'' in the dispute.
(However, UPI reported April 12 that the Soviet Union denies it has encouraged Argentina and says it has nothing to gain by supporting Argentina against Britain.)
There are likely to be limits as to how far the Soviets can go in wooing Argentina. This is in many ways an anticommunist country. Argentina is more than 90 percent Roman Catholic. It has a strong middle class and a Peronist movement, which has been traditionally anticommunist.
Argentina's current attempts to woo the Soviets are considered in part an effort to put pressure on the US. In effect, the Argentines are saying to the Americans: ''If you don't help us, we can always go to the Soviets.''
Argentine officials have circulated a story, carried by at least two newspapers here, claiming that the Soviet Union is supplying Argentina with intelligence on the movements of the British fleet that has been gathered from Soviet spy satellites. The story was clearly designed for American eyes and ears , but it is likely to be seen for what it almost certainly is: disinformation, the term that professional diplomats use to describe information secretly planted by governments in order to influence opinion.
Argentine President Galtieri is considered to be strongly anti-Soviet, and more than a year ago he and other Argentine military officers were reported to have rejected a Soviet offer to sell jet fighter planes to Argentina.
But some observers think that anti-Americanism among some other Argentine military officers could be exploited by the Soviet Union. Such anti-Americanism goes back to World War II, when US officials accused high-ranking Argentine officers of being pro-Nazi.
Argentina came to the support of the allies against Nazi Germany once it became clear that the Allies were winning the war. But the American charges against them left some Argentine military officers and officials with a bad feeling. They accused the US of interfering in Argentina's internal affairs. The late President Juan Domingo Peron was able to exploit the anti-US feeling in a successful election campaign.