In his March 23 speech to the nation on defense spending and policy, President Reagan repeated his earlier claim that the Soviet Union enjoys a ''margin of nuclear superiority'' over the United States. Calling on the Congress and the public to support his massive military budget, the President used electronic graphics and a stream of numbers to buttress his contention that the East-West military balance overall - nuclear capabilities as well as conventional ones - has tilted dangerously in favor of the Soviets.
It isn't so. The US and its allies are strong enough militarily to discourage any plausible Soviet threat to our security, and we can remain so without the massive military buildup to which the Reagan administration has committed itself. The President has been able to suggest otherwise only by presenting an incomplete and misleading picture of the military balance. What has been left out? What is the President trying to sell the American people, and why?
One of the main omissions from the President's portrayal was the relevant military forces of our allies. Repeatedly, he compared US forces with Soviet forces, rather than comparing the forces of the two alliances - the North Atlantic Treaty Organization (NATO) and the Warsaw Pact - that actually face each other as potential adversaries. The Soviet Union accounts for 90 percent of the Warsaw Pact's military spending, while the US accounts for only about 60 percent of NATO's. NATO as a whole spends more on defense and has more military manpower than the Warsaw Pact as a whole.
Other factors unfavorable to the Soviets - and unmentioned by the President - are the questionable loyalty of some of their East European allies and the presence of a billion potentially hostile Chinese to the southeast. The Chinese alone have more men in uniform than the Soviet Union does, and, while the Chinese are much less well equipped, the Soviets have thought it necessary to deploy about a fourth of the Red Army opposite the 7,000-kilometer Chinese border.
The omission of the forces of our European allies and China played an important part in President Reagan's portrayal of massive asymmetry in ''intermediate-range nuclear weapons.'' His electronic chart with this title, showing 1,300 Soviet warheads to none for the US, pertained only to deployments by the two superpowers and indeed only to a subset of those: land-based, intermediate-range missiles. The Soviet missiles in this category are targeted on Western Europe and Asia; they cannot reach the US (other than Alaska). Opposing them, but omitted from the President's chart, are about 400 warheads on land-based and submarine-launched intermediate-range missiles deployed by Great Britain, France, and China, and another 400 warheads on US missile subs assigned to NATO control.
Also left out entirely from President Reagan's comparison of ''intermediate-range nuclear weapons'' were the nuclear-capable medium-range bombers and strike aircraft deployed by NATO and the Warsaw Pact by the hundreds (and by China by the score). The US alone has an inventory of more than 6,000 nuclear bombs available for delivery by such aircraft.
There is room for argument, of course, about the exact numbers and capabilities of these weapons systems. But the overall conclusion is both clear and completely contrary to the message of President Reagan's chart. There are formidable arsenals of intermediate-range nuclear weapons aimed at the Soviet Union, offsetting the ones the Soviet Union has aimed at others. Differences of detail in the composition of these arsenals are made irrelevant by the excessive , almost incomprehensible destructive power of both.
The destructive capacity of the ''central strategic forces'' of the two superpowers - their intercontinental ballistic missiles, their sub-launched ballistic missiles, and their intercontinental bombers - is greater still, but the conclusion is the same: the differences in composition of the forces on the two sides produce no usable advantage for either. Yet the Reagan administration seems determined to dwell on the details, seeking evidence, in the inevitable differences in subcategories of strategic weaponry, for the proposition that the Soviet Union has ''nuclear superiority.''
The administration bemoans the advantage of the Soviet ICBM force in number of missiles and megatonnage. Never mind the asymmetry in this comparison - that the Soviet ICBMs contain 70 percent of the warheads and 75 percent of the megatonnage in their entire strategic arsenal, while the US ICBMs contain only 25 percent of the warheads and 40 percent of the megatonnage in our strategic arsenal. Never mind either that the US has about 2,000 more deliverable warheads in its total strategic arsenal than the Soviet Union does.
In the case of the submarine-based strategic forces, the President complained that the Soviets had deployed four new
types of sub-launched ballistic missiles in a period in which the US deployed only two new types. These figures prove little, except perhaps that the Soviets are trying hard to catch up. By the measures that matter most, the US submarine-missile force remains superior. We have far more warheads in this force than the Soviets do; our sub-launched warheads are more accurate than theirs; we keep a far larger percentage of our missile subs at sea (rather than vulnerable in port) at all times than the Soviets do; and our subs at sea are much less susceptible to detection (and hence destruction) than those of the Soviets are.
As for the intercontinental bombers, President Reagan repeated his administration's lament about the increasing age (and implied obsolescence) of our B-52 force. The oldest B-52s in our force of some 300 of these bombers were deployed starting in 1956, but three-quarters of the force consists of later models with greater range, payload, and mission flexibility. All of the B-52s have been upgraded repeatedly over the past two decades with advanced electronics and other improvements. Many now carry supersonic ground-attack missiles (first deployed in 1972) or air-launched cruise missiles (1982).
By contrast, the entire intercontinental bomber force of the Soviet Union consists of 150 aircraft of the same 1956 vintage as the oldest B-52, but of substantially inferior capability. (Two-thirds have propellers!) The total payload of the Soviet intercontinental bomber force is one-fourth that of its US counterpart.
To downplay the inferiority of the Soviet long-range bomber force, the Reagan administration has decided to portray the medium-range Soviet Backfire bomber as ''inter-continental.'' (The President did so in his speech, as did the Department of Defense in its much-publicized March 1983 edition of ''Soviet Military Power.'') The Backfire - a swing-wing, supersonic aircraft with a bomb load comparable to that of an F-4 Phantom - has an unrefueled combat radius of perhaps 3,000 kilometers. It could reach the northwestern US from Soviet arctic bases near Alaska, but it is not an ''intercontinental'' bomber by the generally accepted definitions.
In any case, the US has its own swing-wing, supersonic counterparts to the backfire: our F-111E/F strike aircraft and FB-111A bomber. First deployed in 1967 (compared to 1974 for the Backfire - the US was ahead as usual), the F-111s have a range around 60 percent of the Backfire's and bomb loads one-and-a-half to two times as great. The somewhat shorter range of the F-111s probably does not console the Soviets much, because we enjoy the use of more bases close to the Soviet Union than vice versa. We deploy a total of about 215 F-111s; the Soviets have perhaps 200 Backfires.
President Reagan made much ado in his speech about the growing ability of the Soviet Union to project military force far beyond its borders. The centerpiece of the President's argument on this point was a set of reconnaissance photographs of military installations in the Caribbean and Central America where Soviet-built radars and weapons are deployed. He characterized the MIG-23 fighters on a Cuban airfield in one of these photos as ''modern,'' as if their presence should be special cause for alarm. This aircraft was first deployed by the Soviet Union in 1971 and now serves in the air forces of Cuba, Syria, Libya, and India, among others. The US has sold many comparable (and better) aircraft to a variety of third-world countries.
Concerning actual ability to deploy substantial forces far from its homeland, the Soviet Union is well behind the US. The Soviets have less than half the long-range military airlift capacity of the US. They have a marine corps of 13, 500 men, vs. 192,000 for the US. The Soviets have three small aircraft carriers, deploying a total of 90 warplanes and helicopters. The US has 14 much larger aircraft carriers, deploying about a thousand warplanes and helicopters.
All this is not to suggest that the Soviet military forces are less than formidable. They do deploy more tanks than all their potential adversaries combined. They have more interceptor aircraft, more heavy artillery, and more submarines than NATO does. NATO, on the other hand, has more major surface warships, more helicopters, and several anti-tank missiles for every Soviet tank.
What does it all mean? There never will be and does not have to be numerical equality in every subcategory of the East-West military balance. With respect to long-range nuclear weaponry, the enormous and secure overkill capabilities of both sides make category-by-category quibbling ridiculous. With respect to shorter-range and conventional weaponry, an approximate overall balance of capabilities is the only sort of equality that is either achievable or worth achieving.
The ''bottom line'' is that neither NATO nor the Warsaw Pact has the sort of clear preponderance of military power that could provide confidence of ''victory'' - of gains outweighing losses - in a major conventional war, much less a nuclear one at any scale. Nor is either side remotely on the verge of acquiring such a preponderance.
Why, then, is the Reagan administration trying so hard to undermine confidence in the military strength of the US and its allies? Can it be sound strategy to try to convince adversaries and allies alike that we are weaker than is really the case? If the fear is that the Soviets will exploit perceived weaknesses in the West to act more aggressively against our interests, how better to encourage them than by fostering an erroneous perception of weakness?
It is always dangerous to speculate on the motivations of others, but in this case it seems essential to try to understand what may be motivating President Reagan and his advisers. The writings, speeches, and interviews of prominent defense strategists in or close to this administration (men such as Richard Perle, Richard Pipes, Colin Gray, and Edward Teller) provide some clues. I believe that this group has concluded - and has persuaded the Reagan administration - that the national interests of the US require that we try to reestablish substantial military superiority over the Soviet Union.
The pursuit of such superiority does have some superficial attractions. It is possible to think that the Soviets will either have to try to match us, doing grave damage to their economy in the process, or let us retake a commanding lead. Either outcome would seem to reduce their ability to stir up trouble around the world.
The one defect in this scheme that the Reagan strategists seem to have perceived is that the American people won't buy it. It is not in the American character to pay for a massive military buildup designed to achieve superiority, all the less when the costs are manifestly squeezing social welfare programs. The American people would only pay for such a buildup if they thought it was needed to catch up. Thus emerges the administration's need to take some liberties with the portrayal of the military balance.
Alas, beyond the obvious difficulty of selling such a program to the American people, the Reagan administration's apparent pursuit of military superiority has some graver defects.
One of them is the supposition that the strain of an accelerated arms race will do more damage to the Soviet economy than to our own. It is true that the US economy is large and more robust than that of the Soviet Union. But it is also true that the mix of goods and services in theirs is much more readily manipulated by government, to military ends, than is the case in ours.
A second defect is the idea that damaging the Soviet economy would benefit the US. It seems at least equally likely that the deteriorating economic conditions in the Soviet Union would increase the belligerency of the Soviet government, if only to divert the attention of the populace away from domestic difficulties and toward foreign ''enemies.''
A third defect is the notion that the US would be able to attain a usable military superiority if the Soviets chose not to ''race.'' The key word is usable. Unless the Soviet Union decides not only not to race but to disarm unilaterally, it will retain enough conventional and nuclear military power to make the costs of US military action against the Soviets' key interests exceed any conceivable benefits. This is the situation that prevails today, in both directions. Under such circumstances, what is the meaning of ''superiority''? How could it be used?
Two dangers in all this are especially acute. First, we seem likely, in the pursuit of an illusory superiority, to deploy (and to stimulate others to deploy in reaction) more weapons whose nature and numbers in themselves increase the chance of nuclear war by mistake or miscalculation. Second is the possibility that, emboldened by a mistaken sense that we actually had achieved a usable superiority, we might try to use it - triggering a conflict that could escalate out of control.
I may be wrong, of course. Conceivably the Reagan administration is not seeking military superiority in the guise of ''catching up.'' But that is certainly what it looks like on the basis of the President's defense budget, his misleading portrayal of the military balance, and the available evidence on the thinking of the strategic analysts most influential in his administration. And that is almost certainly what it looks like to the Soviets..