America's objective in Central and South America must continue to be creation of democratic governments - not just because it's the right thing to do but because it enhances national security.

Retired Army Col. Lawrence L. Tracy, formerly senior defense adviser in the State Department's office of Latin America Public Diplomacy, made that point Friday in addressing a "Global Affairs and U.S. National Security" seminar in the Salt Lake Hilton Hotel.The seminar was sponsored by the Reserve Officers Association of the United States and the New York-based National Strategy Information Center.

Now a consultant to Americans for Democracy in Latin America, an educational foundation, Tracy said it's important to emphasize democratic governments, because those responsible to the will of their people do not wage war on other governments nor do they make territory available for Soviet bases.

"It is imperative for the security of the U.S. that we have no more Cubas in this region," Tracy stressed in an interview and in his address.

Central American and other nearby countries have long been described by Soviet strategic thinkers as the "strategic rear of the U.S.," he said. The countries are, in effect, our "Achilles heel."

The reason for that, Tracy said, is that more than half of U.S.-imported petroleum passes through the Caribbean and the Gulf of Mexico.

"Almost half of our imports and exports likewise pass through these waters, and more than 60 percent of the resupplies and reinforcements that our forces in NATO (North Atlantic Treaty Organization) would require in time of war must pass out of Gulf ports en route to Europe."

He said, "The Soviet Union realizes that if chaos and perennial unrest can be created or fostered by `national liberation movements' carried out by Communist guerrillas that it will cause the U.S. to divert attention and perhaps military assets to this region, which is so close to the U.S."

An added problem for the United States - and of which Soviet leaders are aware - is a massive exodus of political refugees fleeing the fighting and development of communist governments, he said.

In Nicaragua, he said, "conservative estimates are that more than half a million people have fled the country since 1979. . . . If a similar exodus took place from Mexico and the rest of Central America, the United States could be inundated with 15 to 20 million political refugees coming into the southwest part of the United States. That could possibly require the withdrawal of troops from Europe to help maintain law and order in the Southwest."

Recent riots in Miami, he said, could well be just the tip of an iceberg of strong resentment by blacks over the influx of Latin American refugees competing for jobs.