Boston — Western public opinion is clearly heard in the halls of the Kremlin. That, observers agree, is what has been proved by a young woman clutching two red carnations at Boston's Logan Airport Dec. 20, who told reporters that ''I came to the United States of America to stay here.''
With these simple words, the daughter-in-law of dissident Soviet physicist Andrei Sakharov began a new chapter in a unique tale of international human rights.
To some, it is primarily a tale of romance, a love-conquers-bureaucracy triumph as weighty as any Russian novel. After three years of struggling with Soviet authorities, Liza Alexeyeva finally left her family and country to join her husband, Alexey Semyonov, in Boston.
To others, however, hers is more than a love story. It is a saga of international diplomacy, a victory with profound ramifications for dissidents and human rights activists in the USSR. The best known of these is Dr. Sakharov , a developer of the Soviet hydrogen bomb. He is an outspoken critic of the government that has exiled him to the Russian city of Gorky.
Exile, however, has not prevented him from communicating with the West. Last month Dr. Sakharov and his wife, Elena Bonner, began a hunger strike to protest the continued refusal of Soviet authorities to allow Miss Alexeyeva to join her husband, who is Mrs. Bonner's son. The two had known each other as students at Moscow's Lenin Pedagogical Institute in 1977, and were married by proxy in Montana last June.
The strike was highly publicized in the West, and 17 days later the Soviets relented and issued Miss Alexeyeva an exit visa.This past weekend she and her husband were reunited for the first time in 31/2 years.
That very publicity, in fact, may be the heart of the story - proving that even the Kremlin, already peppered with criticism for its role in Afghanistan and Poland, is not immune to Western public opinion. ''Everything is heard,'' said Mr. Semyonov, ''and every voice counts.''
That view is shared by Dr. Cronid Lubarsky, a dissident Soviet astrophysicist who discussed the incident with the Monitor in Boston Dec. 17. After working on the first Soviet manned space flight, and later serving five years in Soviet prison camps, he emigrated to Munich, where he now edits the respected USSR New Brief. ''At first we were very skeptical'' about the hunger strike, he said, realizing how much the outcome would ''depend on reaction from the West.''
But the story, having all the elements of romance, suspense, and international intrigue, was played strongly in Western news media. ''When they (the Soviet authorities) understood the reaction of public opinion was a strong one,'' he said, ''they were forced to retreat.'' Why? Because, he explained, ''they badly need all contacts with the West'' and ''can't live without your help.'' He emphasized the Kremlin's need for grain and high technology trade, as well as their interest in keeping the Geneva disarmament talks alive.
Mr. Semyonov, too, sees the value of such publicity. During the hunger strike, he diligently sought press coverage, mailing out information from his sister's home in Newton, Mass., and holding a press conference in Washington organized by Sen. Paul Tsongas.
Asked at Logan Airport whether his wife's comments might endanger the Sakharovs, he replied, ''It does not put them in danger. It is the only way to defend them.'' He said that the KGB (Soviet secret police) would ''certainly try to revenge'' their loss of face over the hunger strike, ''unless the pressure from the Western countries continues.''
Does that mean, then, that the Kremlin is relenting in its human rights policies? No, says Dr. Lubarsky, who expects persecution of dissidents to harden in the next few years. Nor, he thinks, will Dr. Sakharov be able to use the hunger-strike weapon again - not, in any case, for some time.
Adam Ulam, director of the Russian Research Center at Harvard, agrees. The hunger strike was ''very much a one-shot thing,'' he says. He also notes that Dr. Sakharov has ''used up a great deal of his moral authority'' on what was essentially a ''personal matter'' rather than an issue of ''political importance.''
Why did Moscow relent? Priscilla McMillan, a fellow of Harvard's Russian Research Center and a former Moscow-based journalist and author, suspects that the Kremlin was moved both by press coverage and by representations from President Reagan, France's President Mitterand, and Germany's Chancellor Schmidt.
With such European issues as Poland, the Siberian gas pipeline, and the Geneva disarmament talks all hanging in the balance - and given Europe's longstanding interest in Dr. Sakharov - she feels that the Kremlin had little choice. But she notes that ''most people feel he (Sakharov) picked a very poor case'' on which to expend such energy.