This is to introduce Dr. Galina Orionova, who (there's no getting around it) looks a lot more like a defected Russian ballerina than a defected Soviet intellectual with a Ph.D. from Moscow's prestigious United States and Canada Institute.

For 10 years she served the Soviet government as a specialist in American foreign policy (specifically concerning the Far East). She wrote reports for the top Soviet decision-makers, under the direction of the institute's creator and most celebrated Soviet authority on America, Georgi Arbatov. Then, having reached the rank of senior associate and with the rest of her career "all predictable," she stepped off an airplane at London's Heathrow Airport in May 1979 and took up studies at Oxford University.

She is currently on her first whirlwind, cross-country tour of America, catching up with American academic colleagues she met in Moscow, getting the usual debriefings. In an interview here, she made no pretense of having first-hand insight on crucial questions having to do with Soviet purposes and intentions--or even on the question of how, exactly, the Soviet decision-making process works. That's the part that has to do with how well we are able to read the Soviets.

But her career as a scholar and analyst of America makes her somewhat of an authority on the other question that will help determine whether, at some critical point, an awful miscalculation by one side or the other may trigger a conflict that neither wants. That's the question of how well the Soviet leadership reads the United States.

Orionova's short answer is unsettling. Even among the scholars in Arbatov's institute, she reports, understanding of how the American political system works is limited. "Scholarship" is restricted to reporting from published sources: American newspapers, magazines, books.

"We presented an accurate picture because we were commanded to present an accurate picture which was based on the American facts and the American analysis and American ideas," she says. "We were not asked to give any policy recommendations."

The reporting, she insists, was "very straight." The problem apparently is that even the scholars don't always believe what they report. "Their understanding of foreign policy is much better than their understanding of American domestic politics," Orionova explains. "They don't think politics are important in American decision-making."

And neither, she is convinced, do the Soviets at the top. The classic example she cites is the failure of the Senate to ratify the SALT II arms control treaty. "They don't understand why the president can't just do it. They think the American government is as powerful as the Soviet one. They don't know how the social system of America works."

Do they not trust the institute? Even in that center of scholarship, Orionova contends, "there are a lot of people who think there is no democracy in America. The Soviet reader, whether he is an academic or not, is spoiled by propaganda; he doesn't believe Russian papers and that is why he doesn't believe what is published in American papers as well."

Not all Americans who have dealt with the Soviets--or make it their business to study them--would agree that the gulf in understanding is quite that great. Some contend that the top people merely pretend not to understand the American way of political life--when it serves their purposes. Others put it down to arrogance: the Soviets understand, but they still are insulted when, as in SALT II, their objectives are thwarted by congressional intransigence.

Either way, the effect can be the same, as Sens. Charles McC. Mathias (R-Md.) and Alan Cranston (D-Calif.) discovered in their recent Moscow talks with high Soviet officials. Soviet Foreign Minister Andrei Gromyko, a 24-year veteran of Soviet-American diplomatic dealings, delivered a half-hour "harangue on the virtues of the SALT treaty and why it should be ratified by the Senate," according to one participant.

When Mathias insisted it was dead, Gromyko yielded not an inch. When Cranston, as Senate minority whip, gave it as his expert opinion that there was no hope, Gromyko kept right on insisting that there was.

You can argue that this was a ploy to put the senators on the defensive. But you cannot lightly dismiss the evidence of Galina Orionova, from her insider's vantage point, that Soviet scholars and Soviet decision-makers are genuinely lacking in understanding of how the American political system works. Still less can you ignore the potential for miscalculation that this adds to a relationship that is, at best, precarious.