Once again Poland is in crisis. Once again the Soviet leaders must be wondering what to do with their most troublesome ally. If history is a guide, their response will be in line with what they perceive as Russia's national interest.

But, in the face of mounting economic and political problems in Eastern Europe, where do Soviet interests lie? The answer is no longer as clear as it once was.

The balance of advantage to the Kremlin from its domination over the region has shifted significantly in the last three decades. When the Red Army freed much of Eastern Europe from German occupation in World War II, Stalin seized the opportunity of guaranteeing Soviet security by creating a chain of satellites from the Baltic to the Adriatic.

Since the region's industrial structure was already well developed, the Soviet Union was also able to derive considerable economic benefit from the arrangement. Today, however, the evidence suggests that Moscow's East European empire is no longer such a profitable concern, at least not as originally conceived.

The dilemma facing the Soviet leadership is most visable in Poland, the largest and strategically most important of the "satellites." Politically unstable, Poland has become a threat rather than a buttress to Soviet security. Economically inefficient, it is also an enormous financial drain on a Soviet Union with its own economic troubles.

If the Soviet Union were to invade Poland, the economic and military burdens would increase enormously. Soviet supply lines to East Germany would be endangered by an actively hostile population. The cost of saving Poland from economic catastrophe would fall on Soviet shoulders alone.

The chances are that the latest confrontation between government and unions in Poland over demands for a five-day work week will somehow be defused. But there are other contentious issues in sight, including the peasants' insistence on an independent farmers' union, censorship and calls for the dismissal of corrupt Communist Party officials. Any one of these could provoke a new crisis.

In tackling these problems, the Polish leaders can have few illusions about the inherent good nature of the Soviet regime. But they can hope to appeal to naked Soviet self-interest. They must somehow persuade the Soviet leadership that the way Poland has been ruled up to now is an inefficient way of running a modern society, and that socialism would function better if some political pluralism were accepted.

Or, as a Polish official recently remarked: "We must try to adapt the socialist system to the last quarter of the 20th century."

The Kremlin's dilemma in Eastern Europe is not confined to Poland alone.

Since the energy crisis, the Soviet Union has been supplying oil and gas to its partners in Comecon, the socialist common market, at well below world prices. For hard-headed economic reasons, it would like to put its relationship with its allies on a better financial footing. But political considerations -- the threat of economic hardship breeding yet more instability -- make this very difficult to achieve.

Eastern Europe has changed a good deal since Stalin's day. National differences have emerged and are tolerated by the Soviet leadership. Yugoslavia and Albania have left the Soviet Bloc entirely, Romania goes its own way on foreign policy, and Hungary boasts a market-type economy. The empire is no longer the monolithic camp it once was.

In a private conversation before the Polish crisis blew up, a Yugoslav leader said he detected a steady, if slow, process toward more emancipated relations within the bloc. The model of a socialist motherland surrounded by obedient satellites was being gradually jettisoned in favor of partnership. As the Yugoslav official expressed it: "The Soviet Union wants partnership in the field of economics while its allies seek it in the field of politics."

The Polish experience illustrates the fact that, when expressed, the Soviet leaders are prepared to accept some dilution of their totalitarian institutions. As a result of Poland's 1956 revolt against Stalinsim, the Kremlin accepted the existence of an independent church and an independent peasantry.

Now, it could be argued, the Polish Communist Party and the Kremlin have been presented with one new fact of life: an independent working class. This latest concession, however, goes right to the heart of the Soviet system. Without control over the working class, communism loses its ideological clothes.

With its different cultural and historical traditions, Poland had posed an acute problem for generations of Russian rulers. In the 19th century, the czars perceived attempted liberalization in Poland as a threat not just to the empire's territorial cohesion, but to Russia's autocratic system.

At one point, Czar Alexander I tried to behave as a constitutional monarch in Poland while remaining an autocrat in Russia. But the experiment was reversed by his successor, Nicholas I. After helping to partition Poland out of existence in the 18th century, the czars crushed Polish uprisings in 1794, 1830, and 1863. The failure of one revolt prepared the ground for the next.

The present Soviet rulers face a range of unacceptable alternatives in Poland that can be simplified to three: acceptance of independent unions; focible suppression, by invasion if necessary; and attempts to gradually role back the gains of Solidarity, the independent union, through political and economic pressures exerted through the Polish Communist Party.

Perhaps predictably, in the short term the Soviet leaders have gone for the least imaginative and apparently the least risky alternative, political and economic pressures. But given Solidarity's proven power, it seems likely that this will fail to produce the desired results. The question then arises: how to choose between the other two approaches?

There is little evidence that the Kremlin is seriously thinking of reconstructing its empire on a more pluralistic basis, as acceptance of independent unions would imply. But they also appear to realize that an invasion of Poland would not solve their long-term problems either. So they vacillate.

Empires ruled by old men assisted by huge bureacracies are not in the habit of taking bold imaginative leaps into the future. The best that Poland can hope for is that inert, lethargic old Russia can slowly be nudged into recoginizing where its own best interest lie.