Indira Gandhi came to Washington this week not to change India's relations with the two superpowers but to identify and underline a change that is already under way.
India has been downgrading its relations with the Soviet Union, upgrading them with the United States and Western Europe.
This advertising of India's delicately controlled shift toward a posture of ''evenhandedness'' between the superpowers balances off a similar shift in the opposite direction in China's attitude.
Ever since Richard Nixon went to China in 1972, China has been friendly with Washington and in a state of ''almost cold war'' with the Soviets. But China is now downgrading its US association and seeking a more ''evenhanded'' posture between Washington and Moscow.
These two changes in the attitudes of the prime Asian powers can also be read in the same context with the serious decline in US relations with its allies in Western Europe. President Reagan must be particularly grateful to Mrs. Gandhi for coming to Washington with a let's-be-friends-again smile on her face at a time when the European allies have repudiated the central feature of Mr. Reagan's foreign policy - his ''hard line'' against the Soviets.
Italy, usually among the most docile of the NATO allies, has just joined France, West Germany, and Britain in rejecting Mr. Reagan's attempted ban on building the pipeline intended to bring Siberian natural gas to West Europe.
Much more than just the pipeline is involved here. The European NATO allies simply do not accept, and will not cooperate with, Mr. Reagan's campaign to apply economic pressure to the Soviet Union. The American President is trying to wage economic warfare against the Soviets on the assumption that they are economically vulnerable and that economic pressure applied on them now could weaken their military power and political empire.
To President Reagan, the Russian bear is evil, aggressive, and predatory. It must be punished - although not at the expense of American wheat farmers - for what it did to Poland.
To the West Europeans, the Russian bear is somnolent, inefficient, and trying to hold together a rickety political empire that is eroding at the fringes and might come apart at any time.
Besides, the Europeans do not believe that a breakup of the Soviet empire would in all respects be a good thing. The total liberation of Poland would mean the liberation of East Germany. That, in turn, probably would lead to a reunification of all Germany. Europeans tend to say in public that they want East German liberation. But how many of them actually do want reunification to occur in this century?
The essential fact is that most Europeans, even including many Germans, accept the present situation in Europe. They see it as being probably safer than what might come into being if the Soviet empire were in fact to break up. They would prefer to live with Europe as it is, and do business with the existing Soviet system, than risk the unknown, which Mr. Reagan's rhetoric, if applied successfully, might bring into being.
It is the most important single fact of the power world at this moment that the European allies have refused to join Mr. Reagan's campaign against the Soviets. The men in Moscow must be relieved. At least their problems do not include the danger of being cut off from access to the technology of the West. They are free to concentrate on their main domestic problem - the succession to Leonid Brezhnev - and on their foreign problems, which seem to be multiplying.
The fact of Mrs. Gandhi's presence in the United States now is one example of the decline of Soviet influence among the self-styled ''nonaligned'' countries of the third world.
India is moving away from a condition of semi-intimacy with the Soviets for many reasons. One of them is that the Soviets are less able than the West to help in the industrial modernization of India. Access to the higher technology of the West is probably a first priority to India in its present stage of development.
Another example of decline in the Soviet range of influence is the Middle East. The Soviets are unable to play an important role there, either in the war betwen Iran and Iraq, or in Israel's surge into Lebanon against the Palestine Liberation Organization and Syria.
Soviet weapons have lost virtually every encounter with US weapons in the fighting in Lebanon. If any of the PLO soldiers besieged in West Beirut survive to fight another day, it will be due to Washington restraint on Israel, not to Soviet help. If Syria is spared an Israeli invasion, it will be thanks to the White House, not to the Kremlin.
President Reagan in Washington, not Mr. Brezhnev in Moscow, is the only person who can restrain Israel's Menachem Begin. The serious question in the Lebanon situation is not what Moscow may do but how much restraint President Reagan is willing to apply to Israel's use of American weapons. Mr. Begin's armies could probably take Damascus this week and Aman the week after - if Washington would permit.
As for Iran and Iraq, Iraq was a Soviet client before it invaded Iran. But Moscow found itself unwilling to help the Iraqis when they got into trouble. Moscow tried to be evenhanded, in order to avoid offending Ayatollah Khomeini in Iran. Here is a classic case of falling between two stools. Soviet influence is modest in both Iran and Iraq today.
And if Moscow were tempted to use further force to improve its situation in that part of the world, it would find India even more inclined to turn Westward.
The assumption in diplomatic quarters is that Mrs. Gandhi was in part stimulated toward her American sightseeing trip by the continued Soviet military presence in Afghanistan. She has refrained from publicly condemning that Soviet invasion. But she cannot enjoy having the bear mauling Afghans just on the other side of the Khyber Pass.
Mrs. Gandhi's estrangement from Washington dates from the 1971 war between India and Pakistan. At that time President Nixon ''tilted'' toward Pakistan. He sent an American naval task force steaming into the Bay of Bengal in an unsuccessful attempt to prevent Mrs. Gandhi from detaching Bangladesh from Pakistan and converting it into being a client or protectorate of India, as it is today.
But as of this week, Mrs. Gandhi's chats with Mr. Reagan suggest that she is more unhappy about the Soviets in Afghanistan than she is about US guns to Pakistan. Bygones can be bygones in power politics.
The relations of the great powers to each other are in constant flux. Mr. Reagan's anti-Soviet policies have alienated Western Europeans. But at least Mrs. Gandhi has decided that at the moment Washington is less dangerous than Moscow.