THE STATE OF THE ALLIANCE: THE MISSILE-WATCH

For West German Chancellor Helmut Schmidt the Soviet SS-20 was the last straw. The Warsaw Pact already had conventional superioirty over NATO. Then in the decade of the 1970s the Soviet Union increased the Warsaw Pack tank superiority from 2:1 to almost 3:1 on the central front, its artillery superiority from 1.5: 1 to 2:1 (and almost 4:1 in North and Central Europe).

It closed the logistical gap with NATO. In line with its military doctrine of offensive blitzkrieg, it mobilized Warsaw Pact infantry almost totally for a programmed advance in any operation up to an unprecedented 70 miles a day. It took the technological lead in titanium armor, armored personnel carriers, surface-to-air missiles, range and rate of fire of self-propelled artillery, and tactical bridging.

In addition, the Soviet Union, taking to heart the lessons of the brilliant Israeli use of air power in the opening hours of the October 1967 war, built a modern inventory of fighters and bombers that carried the Soviet Air Force well beyond its previous missions of passive interception of enemy aircraft and, In effect, battlefield use as an airborne artillery, to pose a real challenge to previous NATO air supremacy in Western Europe.

At the same time a remarkable buildup of the previously neglected Soviet Navy meant the United States no longer had assured control of the North Atlantic -- the vital supply line for any war lasting more than a spurt of a few days.

Moreover, there was no hint of any letup in the Soviet military buildup. The "military-party complex" in the Soviet Union seemed to generate an even more inexorable momentum than the "military-industrial complex" in the West. And this, combined with Moscow's perceived bias toward military solutions in foreign policy, worried the whole Western alliance.

Soviet military spending is double American military spending as a percentage of gross national product and exceeds American spending in absolute terms. Total Soviet/Warsaw Pack spending is less than total NATO spending. But given the Soviet conscript's pay of $3 or $4 a month and the American volunteer private's pay of $501.30 a month, the Soviet Union and Eastern Europe still invest a substantially greater amount than the West in actual weapons procurement.

Still, until the late 1970s, the Soviet spending and military buildup was not too alarming. The West maintained (and still maintains) its technological superiority in electronics and avionics, computers, miniaturization of computers and engines, night vision and terrain-following radar, look-down shoot-down systems, precision-guided munitions, remote-piloted vehicles, strategic cruise missiles, airborne radars and missiles, and high-technology engines and airframes.

At least some NATO analysts thought NATO's antitank weapons effectively made up for the difference in numbers of tanks. NATO commanders calculated (and still do) that the West's superior aircraft flexibility and pilot training would enable NATO's 2,000 combat aircraft on the central front (6,000 after all-out reinforcement) to take on the Warsaw Pact's 3,400 (7,000 after all-out reinforcement), fly about the same total of sorties, and hold NATO airspace.

Then, too, the rule of thumb still held in the late 1970s that in any conventional war an aggressor would need a 3:1 superiority to feel confident enough to launch an attack. (In the new era of standoff targeting this may no longer be true.) Apart from tanks and concentrated artillery, the Soviet Union did not and does not have this degree of superiority. And ever since 1956, at least, NATO has deliberately (for reasons of reassurance as well as of cost) kept its conventional force posture visibly inferior to the Warsaw Pact, thus showing that it neither intended to nor was capable to military intervention in Eastern Europe.

Despite some dispute about any bolt-out-of-the-blue "standing start" Warsaw Pact attack, the late 1970s NATO forces were basically considered adequate to deter, and if necessary, repulse, an attack.

Then came the Soviet Union's mobile SS-20. This was a "long-range theater nuclear force" (LRTNF, in the jargon), with a range of up to 5,000 kilometers (3 ,000 miles). Ot carried three independently targetable warheads and was reloadable. Its mobility -- unprecedented in any previous Soviet or American nuclear missile -- gave it relative invulnerability. It had an altogether new accuracy (circular error probable, or CEP) of 300 meters. This combination meant a new capacity for penetration that Western planes could no longer prevent.

For the first time it made NATO's soft rear targets -- missile sites, air bases, command centers -- vulnerable to destruction within minutes of a Soviet launch. The sixfold and threefold improvement in the SS-20 accuracy over the aging Soviet SS-4s and -5s, respectively, also gave the Soviet Union a real nuclear "war fighting" (rather than just crude city-busting) capacity in the European theater for the first time.

The Soviet Union began deploying the SS-20 in 1977 and now has some 150 missiles (out of a Soviet worldwide total of 450 warheads aimed at Europe, according to official NATO figures).

With the SS-20 Moscow claimed that it was only modernizing old medium-range weapons and catching up with the West, not giving a new twist to the arms spiral. NATO already had missiles of comparable range in the four British, five French, and four or five NATO- assigned American nuclear missile submarines.

These dozen-odd subs gave the French 80, the British 64, and the Americans 400 warheads (International Institute for Strategic Studies figures, 1980-81) for use against targets in Eastern Europe and even the Soviet Union. And the comprehensive balance of nuclear weapons of all ranges in or targeted on Europe was 7,500 (pre-1980) or 6,500 (1981) for NATO as against the Warsaw Pact's 3,500 .

NATO took a less benign view of the SS-20s, however. The West claimed an overall European balance of 1,168 NATO vs. 1,995 Warsaw Pact nuclear warheads of everything over 160-kilometer (100-mile) range; when reliability and other factors were tallied in, the comparison was 555 NATO (counting strategic subs and all French systems) vs. 819 Warsaw Pact "arriving warheads" (IISS).

In addition, in drawing up a balance the West was aware of serious inhibitions on the employment of its submarine missiles. The British and French subs were earmarked for national use and would require so much advance consultation for NATO use as to make them unavailable in practice in any fast-moving crisis or outbreak of hostilities. The US subs are only on loan to NATO and are actually part of the US strategic intercontinental missile force. Firing of these weapons would therefore imply an all-out nuclear war; they could hardly be employed to give Moscow a warning signal (as theater nuclear forces are intended to do) not to escalate further.

Besides, the American submarines have already been counted once in the strategic East-West equation. They are part of the 2,056 American and 2,498 Soviet strategic intercontinental launchers under the 1972 Soviet-American Strategic Arms Limitation Treaty (SALT I) -- and tacitly, of the unratified 2, 200 (approx.) each American and Soviet ceilings under the 1979 SALT II. If they are to be double-counted in the purely European balance, then Soviet strategic subs that could hit targets in Europe would also have to be double-counted in the European balance.

The upshot was that Western Europe felt itself threatened by the SS-20. It had interpreted Soviet superiority in less sophisticated LRTNF in the 1960s as a defensive measure. In a period when Moscow lagged well behind Washington in strategic intercontinental missiles, it had sought to compensate for this by holding Western Europe hostage with medium-range weapons. But by 1977 Moscow equaled Washington in strategic missiles. Western europe could see little defensive (as distinct from offensive) Soviet need to develop a sophisticated new medium-range missile to hold to Europe's head.

Basically, therefore, Western Europe -- and especially West Germany -- saw a new Soviet threat to two essentials of its security: "extended deterrence" and "escalation control."

What the new Soviet superiority in relatively invulnerable, quite accurate LRTNF meant, in other words, was that NATO no longer had a viable option of escalating any war it was losing at the conventional level to a more favorable tactical nuclear level.

This shift was crucial, because NATO's whole post-World War II strategy had been to compensate for its numerical conventional inferiority with technological and with short-range tactical nuclear superiority -- and then to reinsure its tactical nuclear superiority with American strategic superiority (in the 1960s), or at least the guaranteed mutual destruction of strategic parity (in the 1970 s). This latter reinsurance was the so-called "extended deterrence" of America's strategic missiles, which should make the Russians pause before launching even a conventional regional war in Europe.

"Extended deterrence" was already being called into question ar the strategic level by the technological spurt in accuracy, the resulting obsolescence of fixed land-based missiles, and consequent doubts about new instabilities in the superpower balance.

When the SS-20 suddenly upset the tactical nuclear balance as well and gave the Russians superiority in the European theater, West Germany especially got worried.

Bundeswehr generals posited a gap in the arms spectrum in which NATO could not answer any SS-20 attack or threat with a response or counterthreat by similar weapons. In such a situation NATO's unpalatable choice would be between a less powerful weapon (which wouldn't be credible) and a more powerful one (which would imply all- out nuclear war). Chancellor Schmidt pointed to this gap in his famous speech at the IISS in the fall of 1977 and asked the US to do something about it.

Initially, the chancellor encountered American resistance to his plea. Washington was less concerned about the SS-20 than Mr. Schmidt was, for two reasons.

First, from the Kennedy through the Center administrations the United States had more or less adhered to a concept of "mutual assured destruction." Nuclear war was so unimaginable terrible, this thesis held, that even a manimum of nuclear capability would deter. No sane leader, even if he had double or triple the other side's nuclear weapons, would think it a "victory" to wipe out 100 million of the opponents' population at the cost of losing 33 or 50 million of his own. Therefore, a little deterrence went a long way, and excessive "overkill" was to be avoided as making the other side nervous.

If agreements on this point could be worked out and signed, so much the better. But if not, then the West should try to induce tacit understandings by some unilateral restraint; a gap in one or another individual system would not be all that risky in the rough overall balance.

Second, the US argued that the American security guarantee for Western Europe had always rested on the explicit "coupling" of European with American defense. No attempt was made in NATO to match the Warsaw Pact tank for tank, precisely because it should always be clear to the Soviet Union that Europe's ultimate defense was the US -- and that the US was as committed to protecting Europe as it was to protecting its own homeland. Any Soviet attack on Western Europe, it should be assumed, would automatically invoke this all-out American defense.

In this context, if the SS-20 had no NATO theater counterweapons, then the obvious counterweapon would be the American strategic missile -- and the "coupling" of Europe with American would be that much clearer. A full balance in Europe across the full spectrum of conventional and nuclear weapons -- especially under the new conditions of superpower parity -- could risk "decoupling," i.e., signaling to the Russians that the US expexted Western Europe to fight primarily on its own.

Schmidt -- and America's own disillusionment with detente -- eventually brought the US around to the German point of view. (In a curious reversal of roles the latter-day Carter -- and especially Reagan -- administration converts became even more zealous than the Europeans on the need to counter the SS-20.)

The NATO governments therefore decided unanimously in December 1979 to fill the gap with weapons that would be the rough qualitative (though not quantitative) equivalent of the SS-20. They planned deployment in the mid- and late 1980s of 572 new Pershing II missiles and ground-launched cruise missiles on West German, Dutch, Belgian, Italian, and British soil.

The new LRTNF would be kept nonthreatening and nonprovocative, however, in staying well below Soviet LRTNF numbers and having only single warheads. They would have a new pinpoint accuracy of 20 to 40 meters' CEP (66 to 132 feet) for the Pershing IIS and less then 80 meters' CEP for the cruise. But the range would be far below the 5,000 kilometers (3,100 miles) of the SS-20 -- 1,000 kilometers for the 108 Pershing II ballistic missiles, 2,000 kilometers for the 464 cruises -- and the slow subsonic speed of the cruises would make it apparent that these were not threatening, "first strike" weapons.

The Russians have hardly viewed what NATO considers its self- restraint on numbers, range, and velocity as reassuring, however. They see, rather, that the cuises -- which can have their terminal guidance programmed to approach a target from any direction -- will compel an expensive Soviet restructuring of what is already the densest and most expensive air defense in the world.

Even more seriously, they in the projected NATO LRTNF systems one all-important innovation: For the first time since John KEnnedy removed obsolescent medium-range missiles from Turkey and Italy in the wake of the Cuban missile crisi, there will again be NATO land-based missile systems deployed in Europe that could strike Moscow, Leningrad, and Kiev. In particular, Pershing missiles, capable of striking the Soviet homeland within minutes, will be deployed on the soil of Russia's two-time invaders, the Germans.

The Russians, who have been trying to court the West Germans to some extent, have so far not stresed this point publicly. But they have noted it privately -- and they have shown no appreciation of Bonn's renunciation of a German finger on the American Pershing and cruise triggers.

As for the European public, not all of its shares the West European governments' anxiety over the SS-20 threat. A majority of voters and politicians in the Netherlands, the Labour Party and a resurgent nuclear pacifist movement in Britain, and a growing minority of young people, Christians , and Social Democratic politicians in West Germany seem to be more worried by the prospect of having LRTNF systems in Europe for the first time in 20 years.

For these people the nuclear angst and moral anguish of the 1950s have been revived. These feelings had been dormant throughout the two-decade search for East-West arms control and detente. They remained sublimated as long as it looked as if the US would ratify SALT II, then proceed to LRTNF arms-control talks. But when a hard-line Ronald Reagan was elected president and declared the death of SALT and the birth of a new arms race, all the pent-up fears resurfaced.

To many leftists and young people, America again seemed -- as it had during the Vietnam war -- belligerent, wedded to conservative authoritarian regimes around the world, spoiling for a showdown with the Soviet Union, and careless with human lives in an increasingly volatile nuclear era. In putting land-based medium-range missiles back in europe the US was seen as restructuring NATO's forces not to deter, but actually to fight, a European nuclear war -- if necessary, to the last European.

In the key country of West Germany (unlike the Netherlands) the anti-LRTNF movement has not yet reached the crossover point to become the single issue uniting the numerous antiestablishment protests. But government officials in Bonn fear it could so if the US is not seen to be taking the LRTNF arms-control talks seriously. In such a case the anti-LRTNF movement could attract a growing number of citizens who have until now accepted West Germany's already dense deployment of tactical nuclear weapons.

If all of this seems surreal -- graduated nuclear war; "signaling" an opponent with a nuclear warhead 10 times as powerful as the Hiroshima bomb; playing a giant game of "chicken" by persuading the adversary that one might be crazy enough to fire these weapons but is still sane enough not to do so unless provoked -- this is because deterrence itself is surreal.

Nobody knows for sure what makes it work. Nobody knows, in an age of potential nuclear holocaust, precisely what combination of force postures, intentions, and inhibitions has so far given Western Europe one of its longest periods of peace in history. Nobody knows just what disruption of the present balance might be fatal.

The common task now -- for Helmut Schmidt and West German protesters, for Mr. Reagan and American hawks, for President Brezhnev and Soviet marshals -- must be to ensure that we never do find out just what makes deterrence work. For the only convincing proof of this would be an ex post facto dissection of why deterrence finally broke down in cataclysm.

The numbers on long-range tactical nuclear forces are difficult to pin down and can be something of a shell game. Essentially, however, according to a combination of official NATO and IISS figures:

Current European balance of high- performance LRTNF Soviet/Warsaw Pact: Warheads on old systems 1,080 (380 single-warhead SS-4s and -5s and 350 bombers with 700 warheads) Modern warheads 620 (150 SS-20s with 450 war- heads, 40-45 Backfire bomb- ers with 160-180 warheads) Total, 1,700 Western/NATO (US strategic subs double-counted): Warheads on old sys- tems 130 (56 aging Vulcan bombers with 112 warheads and 18 French land-based missiles) Warheads of early 1970s technology 884 (400 on US strategic subs, 80 on French subs, 64 on British subs, and 170 British-based American missiles with 340 warheads) Total, 1,014 Mid-to late-1980s balance after development of planned NATO long-range tactical nuclear forces would show approximately: Soviet/Warsaw Pact high-performance nuclear warheads: Old warheads 800 (200 single warhead SS-4s and -5s and 300 old bombers with 600 warheads Modern war- heads 1,000 (200 SS-20s with 600 war- heads and 100 backfires with 400 warheads) Total, 1,800 Western/NATO warheads: Warheads with early '70s technology 740 (340 F-111 and 400 double- counted US strategic subma- rine warheads French and British warheads 162 Warheads with 1980s technology 572 (464 cruises and 108 Per- shing IIs) Total, 1,474