Do you think it's wise to do business with the Russians? Better not suggest it to America's No. 1 hawk, Defense Secretary Caspar Weinberger.

Normal trade only strengthens their economy, increasing their military capability, Weinberger argues. And one way to bring the Soviet Union, now in "economic distress," to a real crunching, is by denying it the $10 billion annually in hard currency that would come from the sales of gas through its controversial pipeline from Siberia to Western Europe.

"There comes a point when additional belt-tightening, even in a Communist country, entails some political risks. Shoppers in Soviet food stores can go along quietly with empty meat counters for months, but can this go on indefinitely?" Weinberger asked rhetorically the other day.

He made this case, in support of the administration's sanctions against European as well as American companies that sell equipment to the Russians for the pipeline, before an international audience gathered here by the Center for Strategic and International Studies of Georgetown University.

U.S. manufacturers report that the sanctions have thrown all export business -- low technology as well as high -- into a state of confusion. To make sure that they are not violating the administration's edicts, the international vice president of a leading U.S. technology supplier told this reporter, many companies are slowing down all exports to the Soviet bloc.

As for the Europeans, they left unconvinced by Weinberger's unyielding rhetoric. They have long suspected that the administration's bitter opposition to the pipeline was triggered not so much by martial law in Poland as by the deeply held view that any trade at all with the Soviet Union enhances its standard of living and, in the end, is reflected in a greater military potential.

By giving a detailed exposition of the Reagan administration view that trade with Russia does not ensure peace, but makes the Soviets a stronger military power, Weinberger confirmed their worst suspicions that this is the real key to the pipeline controversy.

"There is a clear correlation between a nation's military strength and its economic health . . . particularly in an age of high-technology warfare," Weinberger said. Briskly, he ran through a series of statistics to indicate the Soviets' "awesomely growing and very effective military power."

Since the 1920s, he said, the Soviets had used Western credits to beef up their industrial output, eliminate bottlenecks and obtain Western weapons and the latest technology. The United States earlier was "one of the worst offenders" in giving away secrets, he said. "They the Russians exploited the open nature of Western societies, and played off Western companies, and even governments, against each other," he charged.

The Reagan administration remains committed to free trade, he asserted, "but that judgment is and has to be balanced by national security considerations."

At the moment, the administration's analysis -- based on CIA and other reports -- is that the Soviet economy "is in staggeringly bad shape." The degree of "economic distress calls into question their ability to continue their military buildup," Weinberger said. Hence, this is the worst possible time to bail them out with the hard cash that will come from the sales of natural gas.

L. J. Brinkhorst, a member of the Netherlands Parliament, rose to his feet after Weinberger laid out this approach. Since "it can't be the hope" of the U.S. government that the pipeline construction would be halted, he asked:

"Short of expecting a breakup of the pipeline agreement, what courses of action do you see for us to come closer together to face a common threat" in the Atlantic alliance?

Weinberger ignored Brinkhorst's assertion that the pipeline would in any event be built, and responded pleasantly enough that partners could disagree, but must stay close together. "NATO must be strong and united," he assured. Yet, Europe should look to alternate sources of energy, and if Europeans really believe in a return to the "glimmering freedoms" that had been seen in Poland -- there was just a hint that Weinberger thinks the Europeans aren't convinced of that need -- they could line up with Reagan, and prevent enlarging the Soviet military potential.

No give, there. So Sir David Nicholson, a member of the European Parliament, tried another tack:

"How can it be that alternative sources of energy were not covered in consultation processes a long time ago, including those which we have through NATO? I think this is the kind of thing which concerns some of us, as to whether we're getting our forward thinking, consultation and planning adequately carried out."

Weinberger acknowledged that "long before we got to Washington" (that means, during the Carter administration), the dangers of the pipeline should have been foreseen. "But essentially, we think we're now faced with a situation that adds to the danger, the problems of all of us in maintaining the balance of deterrence . . . " As for the other sources, he pointed to Britain, Norway and Holland, in effect inviting them to boost their sales to the rest of Europe.

At this stage, Thierry de Montbrial, director of the French Institute of International Relations, stepped to the microphone and laid bare the sharp edge of bitterness that exists between Atlantic partners:

"As you know, most Europeans differ with your analysis," De Montbrial told Weinberger, "for instance on the relationship between trade and the Soviet behavior in Poland. Most Europeans think that the sanctions decision will do much more harm to the Atlantic alliance than to the Soviets. If this is so, how can we have a pipeline truce?"

Now Weinberger's voice took on an edge: "I think they the sanctions will only do harm to the alliance if the European countries and the United States allow it to do harm." If the Europeans simply follow the U.S. lead, Weinberger said, conditions "would improve" in Poland, and the pipeline issue would disappear as a contentious issue in the alliance.

Europeans simply do not believe that is possible. Simone Veil, the distinguished French political figure, now a member of the European Parliament, indicated in a conversation that with the benefit of hindsight, many Europeans may now wonder about the wisdom of the pipeline deal. But Europe, she said, is now so irrevocably committed that to back away would cause a new economic disaster.

"That," she said sadly, "is what I think your government fails to understand."