For two countries as closely aligned as India and the Soviet Union, the undercurrent of tension between them is amazing and quite palpable in New Delhi. Friction has developed especially over trade, but also encompasses the policies of the pro-Moscow Communist Party of India.
These developments do not change the basic thrust of Indian policies toward the Soviet Union, but they are a reminder that the relationship is mainly a marriage of convenience. Members of the Indian elite say, almost with resignation, that given United States policies in the South Asia region and the geopolitical realities, the country has no option but to maintain close links with Moscow.
The Soviet Union is now India's largest trading partner and is its biggest supplier of arms. There are, of course, any number of persons in the ruling establishment in New Delhi and outside it who are greatly devoted to the special relationship with Moscow. But what has been described as a ''tiredness'' in this relationship is throwing up longer shadows.
Indo-Soviet trade has prospered over the years on a barter arrangement for balanced trade on the basis of settling accounts in Indian rupees. But after the first phase of Indian industrialization, the magic of the rising trade graph is dissipating, with India accumulating mounting surpluses.
With economic liberalization policies initiated by Prime Minister Indira Gandhi in the last two years, Indian importers would rather go to the West or Japan for modern technology. Soviet exports to India have therefore been languishing, except for such staple and welcome items as crude oil and petroleum products.
To make the point, the Soviets stopped buying cashew nuts and reduced textile quotas, creating major problems for Indian producers. Nobody in New Delhi believed the Soviet argument that they had to substitute almonds for cashews because they needed to buy almonds from Afghanistan to support that country.
India's large arms purchases greatly offset its other trade purchases, but the Soviets have been insisting that New Delhi buy more in the field of heavy machinery. The Indian government is committed to exploring ways of increasing machinery purchases from the Soviet Union.
The Communist Party of India (CPI) has been a source of irritation for a succession of Indian leaders. During the short-lived rule by the coalition Janata Party (1977-80), Prime Minister Morarji Desai lectured Soviet Premier Alexei Kosygin on the evils of interfering in Indian affairs.
Being better schooled in the realm of real politics, Mrs. Gandhi has used the CPI for her own ends. The pro-Moscow party supported her during the emergency regime (1975-77). In an effort to shake off the unpopularity associated with that regime, the CPI later reversed its support for Mrs. Gandhi, although also with a view to seeking better relations with the other, stronger communist party , the CPI (Marxists).
Mrs. Gandhi has made a public issue of the CPI's policies, not only domestically but also with the Soviets. She has suggested, in effect, that the Soviets should tell their client party to support her.
Moscow has made some gestures toward getting the CPI to support her, without apparent success. An assumption being made in New Delhi is that with general elections due within a year, the Soviets are loath to put all their eggs in Mrs. Gandhi's basket. They were badly burned in the 1977 elections, which saw Mrs. Gandhi's defeat and the coming to power of the oppositionist Janata coalition they had termed reactionary.
Enlivening this controversy is a bizarre episode of a letter Mrs. Gandhi sent to Soviet leader Yuri Andropov through a member of the CPI which surfaced recently. The letter, timed with the Soviet's June observance of the victory over the Nazis celebrated, made the point that the political left in India - meaning the CPI - was hindering her work, rather than helping her.
The bearer of the letter, Yogendra Sharma, was not received by Andropov (perhaps because of ill health), and the Soviets took the precaution of informing the CPI of what the letter said. Sharma was later expelled from the CPI's major policymaking body, an action that further exacerbated divisions in the party.
The anti-Gandhi faction has a majority in the Communist Party of India, although Mrs. Gandhi still has sympathizers who would rather have the party support her. Meanwhile, the prime minister continues to hold the Soviets responsible for the CPI's conduct.