The Curtain Rises: Eastern Europe, 1989 : SOVIET UNION : Gorbachev Unleashes the Forces of Reform : A hands-on crisis manager, his intercession has proved crucial in toppling the East Bloc’s hard-liners.

Negotiations between Poland’s Communist leaders and Solidarity over the new coalition government in Warsaw were at an impasse last August.

The issue--how much power the Communists would have--was central to formation of the Solidarity-led coalition and its prospects for success. Resolution of the dispute was crucial, all agreed, but after more than four decades in power, the Communists were finding it difficult to accept Solidarity’s control of the government.

Then, at the peak of the crisis, on Tuesday, Aug. 22, a telephone call came from Moscow, from Communist Party headquarters here, from Mikhail S. Gorbachev, the Soviet president and the party’s general secretary. For 40 minutes, Gorbachev talked with Mieczyslaw Rakowski, the first secretary of the ruling Polish United Workers’ Party, and counseled him on the need for compromise.

The Polish Communists must understand, Gorbachev told Rakowski bluntly, that the time had come to yield power. The party had lost the confidence of the people--as the parliamentary elections in June had shown--and it would have to work to regain it, he said. For the salvation of the nation, Polish Communists should participate in the new coalition government, Gorbachev said, and they would have the understanding and support of their Soviet comrades.

The impasse was broken. That afternoon, the party dropped its demands for greater powers in the coalition and declared its readiness for “partner-like cooperation” with Solidarity.

Four days later, Vladimir A. Kryuchkov, the head of the KGB, arrived in Warsaw to confer with Tadeusz Mazowiecki, the Solidarity nominee for prime minister, and to give the new coalition government Moscow’s blessing.

Gorbachev’s call, as recounted recently by one of his foreign policy advisers, had altered not only the course of Polish politics but of subsequent events throughout Eastern Europe.

For he has proved to be very much a hands-on crisis manager: He has himself intervened at crucial moments not only in Warsaw but also in Berlin.

He maintains daily contact by telephone and telex with Soviet diplomats, party envoys and military commanders throughout the region, according to informed Soviet sources. And he has interceded personally with top Western leaders to ensure that developments proceed smoothly.

The Soviet Union, caught up in its own political and economic reforms, was suddenly encouraging other socialist countries to democratize, to decentralize their planned, state-managed economies and to pursue with greater vigor the long-delayed de-Stalinization of their societies.

“The biggest and most essential reforms began in the Soviet Union,” Foreign Minister Eduard A. Shevardnadze reminded journalists last month.

However pressing the problems may have been in Warsaw or other East European capitals, no one had forgotten that, in August, 1968, Moscow sent Warsaw Pact forces into Czechoslovakia to end the Prague Spring, that country’s experiment in liberalization; that Moscow had pushed Poland into declaring martial law in 1981 to deal with Solidarity, and that it had used Soviet troops to crush earlier anti-Communist uprisings in Hungary, East Germany and Poland.

But Gorbachev, setting out the Soviet Union’s new foreign policy at the United Nations last December, had declared: “The principle of freedom of choice is mandatory. Refusal to recognize this principle will have serious consequences for world peace.

The crucial test of Moscow’s “new political thinking” came, as everyone knew it would, in Eastern Europe, which the Soviet Union had turned into a strategic and ideological buffer after World War II through an array of “people’s democracies” intended to protect both the motherland and Communism from the capitalist West.

“We knew some time ago that things could not last there, not the way that they were, not with all those years of problems piled up,” Leonid N. Dobrokhotov, a foreign policy specialist at the Communist Party’s Central Committee headquarters, said in an interview. “But we did not expect the changes to come so quickly and so dramatically.”

And through all this, the Soviet Union, surprising itself as much as any Western observer, has supported and even helped promote the transformation.

The old leaderships in Berlin, Prague and Sofia were warned directly by their comrades in Moscow that the time had come for a change, that reforms could be delayed no longer and that they could expect no Soviet support in clinging to power.

When the Czechoslovak party newspaper Rude Pravo bannered Moscow’s frank advice to the leadership there to “reassess” the way it had come to power in 1968, the crowds in Prague’s Wenceslas Square swelled to unprecedented size--and the Czechoslovak party’s will to govern was probably lost.

And the unexpected emergence last month of a reformist “Gorbachev generation” to replace the Bulgarian Communist Party’s aging leadership had been actively, though quietly, encouraged by senior Soviet leaders, including Shevardnadze.

“The changes in the socialist countries are as unavoidable today as they are desirable,” Dobrokhotov argued.

But Moscow has been very concerned that the transformations proceed as smoothly as possible.

For Moscow, the changes in Eastern Europe have wide ramifications. The empire of satellite states that dictator Josef Stalin so painfully assembled is gone, but Gorbachev appears happy to be relieved of what had become a politically expensive burden. Moscow’s authority, Soviet analysts believe, has even been enhanced by Gorbachev’s adherence to his U.N. commitment to “freedom of choice.” And the Kremlin’s attention, Soviet observers say, can now turn to the country’s most critical problem--rebuilding the economy.

The most immediate Soviet concern, however, is the reunification of East and West Germany. Not only is East Germany a strategic ally--the Soviet Union has 380,000 troops stationed there--but, in Moscow’s view, it is the key to balance of power between East and West. While leaving to “history” the possibility of eventual reunification of the two German states, Moscow has strongly opposed a Bonn plan to speed up the process.

Another serious worry is the possibility that some members of the Warsaw Pact, perhaps Hungary or Poland, will decide to quit, upsetting the military balance between East and West.

What Moscow wants most of all to see emerge from Eastern Europe’s transformation, Gorbachev has said repeatedly, is a commonwealth of European countries--some socialist, some capitalist and many in between--that ends the post-World War II division of the Continent.

In all this, there is what one Soviet commentator calls “the big what-if”: What if Gorbachev fails at home and is replaced by a conservative?

The answer, worked out by those Soviet think tanks that have advised Gorbachev for years, is that the changes in Eastern Europe will soon be irreversible, at least from outside.

But there is a deeper worry here--a real fear, in fact--that the changes in Eastern Europe and Gorbachev’s declared commitment to “freedom of choice” could bring the disintegration of the Soviet Union as some of its constituent republics exercise that freedom and break away.

The political movements developing in the three Baltic republics of Estonia, Latvia and Lithuania stem from the same heritage as those in Eastern Europe.

Some nationalists in Armenia, Georgia and the Ukraine, as well as the Baltics, are demanding full independence from Moscow; others want acknowledgement of their sovereignty in return for what is really autonomy within a new federal system.