The United States faces "potential challenges" in Third World countries and may become isolated from its European allies as a result of the Soviet Union's military superiority, a State Department expert said yesterday.

Speaking to about 50 people at the Russian Research Center, Jeremy R. Azrael '56, senior adviser on Soviet affairs in the U.S. Bureau of Politico-Military Affairs, said that the Soviets are prepared to "exploit low-risk targets" in areas where the U.S. is "powerless" to intervene, and that Soviet arms buildups will continue through at least 1985.

"We are in long-term competition with a competitor whom we have not always understood," Azrael, a former professor of political science at the University of Chicago, said.

The Soviet Union has been engaged in a "massive military buildup since 1965," he added, saying that many new military systems, including ballistic missiles, intercontinental bombers, and aircraft carriers, are ready for testing and production, and that these new systems will continue to open a "window of opportunity."

Although a "determination to match the U.S." was a crucial factor in the Soviet decision to increase defense spending, there was also a desire on the part of the Soviet leadership to practice "political intimidation" against Europe, Japan, and China, Azrael said.

By reaching the current level of "strategic parity plus," he added, the Soviets have come from a position of "gross strategic inferiority," and have gained several new "power projection" capabilities in Western Europe.

Azrael maintains that Soviet leaders have "knowingly sacrificed" the industrial future and consumer welfare of their country in favor of military acquisitions, which, he said, they consider to be "extremely valuable and desirable."

"They are now very big, very rough, and very tough," he added.

In reacting to Soviet military superiority, Azrael said, the U.S. should consider a "careful ordering of priorities," and should seek an arms control program that would "redress imbalances."

"We are not likely to see a lot of self-restraint," he added, until the Soviets "recognize the risks" of continuing to sacrifice their country's future well-being.