A warning by Soviet human rights activist Andrei D. Sakharov that the West has more to fear from the failure of Kremlin reforms than from their successes goes to the heart of a dilemma facing George Bush as he prepares to lead American policy."The threat of perestroika doesn't consist of its success but of its bloody failure. This would be a total calamity," said Sakharov, conjuring up an image of a newly militant Kremlin again embracing the totalitarianism and expansionism of the Stalin era.

With Sakharov's words still ringing, Bush must ask himself how to deal with Gorbachev's faltering reform program. What arms control concessions can the United States afford to make? Should Washington keep pace with Western Europe in making trade deals with the Kremlin?

Bush has said he favors an early meeting with Gorbachev to discuss such issues as sharp cuts in strategic nuclear weapons, reducing the size of conventional armed forces in Europe and finding a way to control the spread of chemical weapons.

If Gorbachev continues the pattern he set during his first three years in office, he will bombard the United States with "peace proposals."

Bush will be under pressure from U.S. allies abroad and moderates at home not to seem frozen in a Cold War mentality. To lose the diplomatic initiative to Gorbachev would give the appearance of trying to undercut his reforms.

Hardline conservatives in the United States, including many former aides from the first Reagan administration, have warned that perestroika, or restructuring, could produce a more vigorous Soviet Union, better able to match the economic and military advances of the West.

But many American experts on the Soviet Union disagree. They say there is little that Washington can do to bolster or undercut Gorbachev's efforts, which the Soviet leader has said face considerable opposition at home.

Complicating the debate is the perception of some U.S. Sovietologists that Gorbachev is trying to outflank Washington by building bridges with U.S. allies in Western Europe and Japan.

Jerry F. Hough of Duke University warned recently that the promotion into the two top Communist Party foreign policy jobs of Aleksandr Yakovlev and Valentin Falin in September marked the ascension of two men who have been publicly hostile to the United States.

"The architects of an American-centered policy - Andrei A. Gromyko (the former foreign minister) and Anatoly Dobrynin (the former Soviet ambassador to Washington) - have been shunted aside," Hough wrote in a Nov. 4 opinion piece in the New York Times.

"Ultimately, the argument about whether or not to help Mr. Gorbachev misses the point. Washington must begin to work with Moscow and stop attaching conditions to cooperative ventures. If we don't, we may one day find ourselves the odd man out, economically and militarily," wrote Hough.

Other analysts believe Gorbachev is already in domestic political trouble, that there is little the United States can do to help or harm him and that he is interested in good relations with America, as well as with the rest of the West.

"The biggest problem that the United States faces now is being blamed by our allies if Gorbachev fails," said John Van Oudenaren, a RAND Corp. expert on Soviet relations with the West.