IT WAS GOOD to have Rajiv Gandhi, India's new prime minister, in town. His manner was winning and his approach to the United States relatively sympathetic. As often as it is said, it remains true that the democratic character of the two countries is mutually gratifying and gives them an advantage in working out the subtle and not so subtle tensions between them. These tensions arise from real differences in culture and development and, more, from an abiding disagreement over the political structure of the Asian subcontinent.

India's view is that South Asia is a region in its own right, that India is dominant in it and that its dominance, specifically over Pakistan, should be acknowledged by all. That Moscow makes this acknowledgment fully and that Washington does not encourages "nonaligned" Delhi's familiar pro-Soviet tilt.

The United States has seen South Asia not just as a region but also as an arena of the East-West contest. This is the basis of the American military tie to Pakistan, a country that successive American administrations have regarded as a useful friend and India regards as an upstart that craves revenge for three lost wars and may yet tempt a fourth, this time with a (stealthily built) nuclear bomb in hand. That India has already exploded a (stealthily built) bomb is taken by Indians as something of a natural right which they need explain to no one.

This abiding disagreement extends to Afghanistan. India has politically comforted the Soviet invaders. The United States has supported the armed resistance to them. In Washington, Mr. Gandhi spoke somewhat more emphatically than he has about the urgency of an Afghan political settlement. But it would be a surprise if India, content as it is with Moscow's policy in the subcontinent, were to push the Kremlin much harder on Afghanistan. There may be solid geopolitical grounds for doing so: India's need to keep Pakistan a sturdy buffer against Soviet encroachment and its exposure to Soviet strategic encirclement. But Delhi is not guided exclusively by this larger view.

Rajiv Gandhi's relative youth (he is 40) and his technological bent fit nicely with the development requirements that India was already perceiving when he took office. Spotting the opening, the United States has moved briskly to offer the requisite high technology and encouragement to free enterprise. This is important. The Indians are chary of buying weapons from a source likelier to tie tighter strings on their use than do Delhi's Soviet suppliers, but over time this too could become a larger area of Indian-American cooperation. It is worth both countries' striving for it.