Thanks to Leo Welt, Muscovites can bowl strikes. Right there on Moscow's Gorki Square is an American-style tenpins bowling alley, courtesy of a Washington-based international trade broker who puts American businesses together with foreign customers, often in countries where free enterprise is a dirty phrase.

"When you deal with state-controlled economies, all business is dependent on politics," says Welt. Harmonious relations can mean potential customers, though Welt says even if the Soviet Union and the United States become cozy by reaching agreement on SALT II, business won't boom to the extent it might. He says a prominent American businessman reported, after a recent meeting with Soviet officials, that "of the 28 big projects in the new five-year plan [which begins this year], the United States has been excluded because we've been unable to compete with long-term, low-interest credits."

More willing to offer generous financial arrangements are Japan and the countries of Western Europe, though Welt says the Soviet Union must still do business with America to acquire certain high technology products unavailable elsewhere.

Orphaned as a child, Welt came to the U.S. from his native West Berlin and attended Princeton University before beginning his career as an internationall peddler of newsprint and pulp products in Africa and the Middle East for International Paper in 1958. Today Welt, 44, maintains an office on K Street from which he oversees a trading company, travel agency, newsletter publishing company (biweekly reports on business abroad), and a new firm that will use barter as a basis for payment.

Welt says barter will be an increasingly important way of doing business in the '80s.

It was while arranging for the U.S.S.R. to purchase from Brunswick Corporation the bowling equipment now in Gorki Square that Welt decided to open his own bowling alley in Germany.That's turned out to be a marginal operation at best. "I'm a better salesman than I am an operator," he admits.

Footnote: Welt has also invested some money in his adopted hometown -- he is an investor in the Capitol Hill American Cafe. Between monthly trips abroad, he swims laps in his indoor pool at his home in the Foxhall area. For fun he is a mechanic; he recently built a treehouse complete with electricity for his two young children.