The United States is superior to the Soviet Union in most areas of military technology. Where it lags behind the Soviets is in its determination to put that technology into weapons and build up its defenses, says President Reagan's science adviser.
George A. Keyworth, one of the most influential science advisers to work in the White House in some years, cites the debate over the MX missile as an example of the gap between America's technological strength and its inability to resolve differences and actually deploy weapons. When it was first conceived, says Dr. Keyworth, the MX was far more accurate than any missile the Soviet Union could produce.
Today, says the bespectacled, boyish-looking science adviser, the Soviets have achieved ''comparable accuracy.'' According to Keyworth, Soviet advances in military strength, including an advantage over the United States in numbers and size of its land-based missiles, have given Kremlin leaders ''a lot of leverage to be . . . quite aggressive in extending their influence.''
Keyworth, a physicist who had considerable experience dealing with nuclear weapons technology at the Los Alamos Scientific Laboratory, was interviewed prior to a bipartisan presidential commission's delivery to President Reagan on April 11 of a report on strategic forces. The report calls for the deployment of 100 MX missiles in existing silos during an interim period, to be accompanied by research and development on small, one-warhead missiles.
The 10-warhead MX has been widely criticized in Congress for being too vulnerable to Soviet attack and too threatening to the Soviets. The Reagan administration has been arguing, however, that the MX is needed to give the US leverage in arms control negotiations with the Soviets and to offset the Soviet advantage in big, land-based missiles. Dubbed ''Midgetman,'' the small missile is only 1/10th the size of the MX. It could easily be made mobile and thus be more easily hidden from a potential attacker.
Keyworth said there were still many unanswered questions as to how a small, single-warhead missile would fit into America's strategic forces. He said that it was ''very much worthy of study,'' but added, ''I think we're a long way right now from seeing a small missile in a basing mode that will significantly enhance our land-based ICBM capability.''
The science adviser said that one development that has gone largely unnoticed outside scientific and military circles has been a growing US ability to ''superharden'' the silos that would contain the projected MX missile. The issue is important partly because much congressional criticism has focused on the apparent inability of successive administrations to find effective ways of protecting the MX.
''This country really hasn't focused on superhardening for a long time,'' said Keyworth. ''. . . There are new ways of calculating, of theoretically modeling, structural systems. We have learned some important things and we've had some important experiments in the last year that make us much more confident in our ability to do the superhardening.
''The question of the MX missile and the land-based ICBM is a very tough problem for a rather fundamental reason: Many decades ago, the Soviets chose to . . . develop a missile capability which was what we would call relatively primitive in terms of accuracy, and they compensated for the accuracy with large-yield weapons.
''We, in turn, had higher technology, and we didn't feel the need for such big missiles, and such big weapons, because we could see higher accuracy. Well, now we're decades beyond that, and the Soviets have comparable accuracy - and gigantic missiles, gigantic warheads, and lots of them.
''And the fact of the matter is that the Soviets have a somewhat more capable land-based ICBM capability today, and it will become even more capable as time goes on. We're trying to address that issue with MX and a survivable basing mode for MX.''
One arm of the so-called triad of strategic nuclear forces - land-based ICBMs , submarines, and bombers - ''is clearly threatened'' by the Soviets, said Keyworth of US land-based ICBMs.
''The nation is not threatened, because we still possess, in particular, the strategic submarine deterrent,'' said the science adviser. ''But you have to ask yourself, of course, if that were ultimately threatened, then wouldn't the nation be threatened with a potential first strike by the Soviets, and the answer is yes.''
At the same time, Keyworth said the US had the lead over the Soviets in submarine technology as well as in the techniques of anti-submarine warfare.
''If you ask me where the Soviets are superior, I will only be able to find a few things that the Soviets do have - an attack submarine (Alpha) that can go deeper and faster than anything the US has,'' said Keyworth. ''On the other hand , I don't think it's a terribly important weapon.''
Keyworth said that despite the US technological lead, the Soviets have been able to close the technological gap through highly effective espionage and through the subsidiaries of high-technology companies that ''tend to leak technology.''
Keyworth said that at the moment priority items for Soviet spies would be the technology that goes into US antisubmarine warfare and into the projected radar-evading Stealth bomber.