Bonn — A discreet shudder shook Bonn this month when four former top American officials proposed a NATO policy of no first use of nuclear weapons.
The conspicuous discretion stemmed from the wish not to give antinuclear demonstrators ammunition to use against Chancellor Helmut Schmidt at this week's convention of the Social Democratic Party. The only official comment has been an oblique rejection of the concept by the foreign minister.
But the shudder was real, however carefully controlled.
The first reason for concern, officials explain, is West Berlin, that island of a city surrounded by East Germany. West Berlin is defenseless in terms of conventional weapons. Its protection in the almost four decades since the end of World War II has therefore resided in the Western threat to make any Soviet-bloc takeover of West Berlin a causus belli -- and a nuclear causus belli at that.
The second reason for West German worry is the perennial NATO inferiority to the Warsaw Pact in quantitative conventional terms. Ever since the early postwar years the West has calculated that it could not sustain the political and economic burden of matching Soviet-bloc conventional forces. It has offset this Soviet advantage instead by superior Western technology and nuclear weapons.
The third reason is really an elaboration of the second: the utter improbability (in Bonn's view) of NATO's ever going ahead with the essential adjunct to a no-first-nuclear-use doctrine -- the building up of its conventional defense into a convincing deterrent by itself.
The deterrent is the crux of the matter, for the security both of West Berlin and of West Germany as a whole. West Germany's wish to preserve the nuclear option -- or at least Soviet uncertainty about it -- reflects no eagerness to use nuclear weapons in battlefields that would certainly be West German. It reflects rather the conviction that the very horror of nuclear weapons and their prospective use helps to deter any war at all much more effectively than any less horrible weapon would.
The fourth reason for West German concern is summed up in the phrase ''Pandora's box.'' Almost any reopening of fundamental nuclear issues, no matter how justified, quickly strains both transatlantic relations and the domestic consensus on defense.
In the most recent example, Chancellor Schmidt's alarm about the new Soviet nuclear superiority in Europe in 1977 nudged NATO to the countermove of planning new nuclear missile deployments in the mid-80s. But it also triggered US-West German squabbles and a resurgence of antinuclear protest in West Germany.
Bonn therefore dreads risking the unpredictable emotional upheavals inherent in any basic nuclear review.
One particular aspect of the syndrome that adds to West German anxiety is the volatility of strategic opinions in succeeding US administrations and in American public moods.
Thus, Schmidt convinced a more dovish President Carter of the need to counter the new Soviet SS-20 missiles in 1977-78 -- only to see the Carter administration swing to a much more hawkish stance after the Soviet invasion of Afghanistan. Indeed, American suspicions began to surface that West Germany itself was too soft on the Soviet Union.
Hawkish American public opinion then elected Ronald Reagan president, with a mandate for a major buildup of the American military. Yet a bare 17 months later there is an antinuclear groundswell in the US that might well come to regard continuing West German government worry about a European military balance as too demanding.
These pendulum swings are unnerving to West Germans. They value steadiness and predictability. They much prefer gradual policy evolution to dramatic switches. They don't want to stimulate any more such swings than they can help.
All this is not to say that Bonn wants to freeze current NATO nuclear contingency planning in perpetuity. At least some West German planners would welcome a shift of operational plans under the deliberately ambiguous doctrine of flexible response much more in the direction of conventional defense. They would like to leave the primary (but still not sole) mission of NATO nuclear weapons as deterring (not fighting) Soviet nuclear weapons.
Summing up Bonn's caution about any categorical renunciation of nuclear first use, then, deputy government spokesman and defense specialist Lothar Ruhl notes that any change in NATO doctrine on first use of nuclear weapons ''is irrelevant to the basic problem posed by the threat of the Soviet conventional superiority in Europe and the nuclear superiority embedded in the SS-20 and other (shorter-range) nuclear options.''
The problem with the West German government (and Reagan government) opposition to any reconsideration of nuclear first use is that times have changed dramatically. The threat of a Western nuclear response to any successful Soviet-bloc conventional attack was credible during the American strategic and tactical nuclear superiority of the 1950s and '60s. But in the '70s the Soviet Union attained strategic parity with the US and then nuclear superiority in the narrower European balance.
Today, it no longer makes much sense for NATO to escalate conventional war to a nuclear level that is much more destructive but no more favorable to the West.
This at least is the argument of McGeorge Bundy, former national security assistant to President Kennedy; George F. Kennan, author of America's postwar containment policy toward the Soviet Union; Robert S. McNamara, Kennedy defense secretary and former World Bank president; and Gerard Smith, chief US negotiator of the first Strategic Arms Limitation Treaty (SALT).
In the spring issue of Foreign Affairs, they contend that it's time to move to a policy of maintaining NATO nuclear weapons only to deter Moscow's own first use of nuclear weapons, and not to deter a Soviet conventional attack.
These four are only the most prominent in a growing list of British, American , and other NATO thinkers who are seriously pondering a European nuclear doctrine limited to reactive use after any first use of nuclear weapons by the Soviet Union. The corollary cited by all the innovators is the strengthening of NATO conventional forces.
The alternative of an exclusively conventional deterrence has long been promoted in a casual way by antinuclear protestors. (Soviet conventional superiority isn't really so great or perhaps doesn't exist at all, this argument runs, and a ''small unit'' defense in place of the present fixed-position ''forward defense'' could in any case compensate for Western inferiority.)
What's new now is that a number of distinctly nonutopian specialists are also beginning to investigate the possibility. The most serious exploration is a two-year study recently undertaken by a blue-ribbon panel of Americans and Europeans commissioned by the American Academy of Arts and Sciences.
On this issue, however, the West German government still maintains that categorical renunciation of nuclear deterrence and total reliance on conventional deterrence (1) could be undesirable and (2) surely is unrealistic.
Thus, the whole postwar coupling of the US to European defense -- a guarantee that has preserved peace here for the longest period in this century -- has rested on two pillars: the stationing of US troops here who would be immediately engaged in any hostilities; and potential escalation of any conflict to involve American nuclear weapons.
Dismantling one of these pillars, West Germans reason, could easily lead to a European (and Soviet) perception that the US commitment to European defense had weakened.
In addition, West German officials are highly skeptical about the willingness of NATO members to foot the more expensive bill that extensive restructuring and equipping of NATO's conventional forces would require.
Nuclear forces are substantially cheaper than conventional forces relative to their impact on a military balance. And the extra investment needed to produce a fully credible conventional force posture is hard to find in a recession-hit Western Europe with strong antinuclear and potentially antimilitary protest movements.
The limits on NATO's options for substituting conventional for nuclear defense are all the more apparent, West Germans believe, when the Soviet erosion of the West's technological lead over the past decade is taken into account.
In this period Soviet aviation has moved from a very limited role of air support ''artillery'' to an offensive role in Europe. Soviet aircraft have come to outnumber NATO aircraft on the central front, and Soviet airplane technology (though not avionics) now equals the West's, pending deployment of new Western models. Soviet-bloc battle tanks outnumber NATO's by 4 to 1. Soviet artillery technology, MI-24 helicopters, BMP armored personnel carriers, surface-to-air missiles, and some other systems surpass their Western counterparts.
The current picture isn't bleak. Defense requires less strength than offense. The West still excels in electronic counter and counter-counter measures, in computers, integrated circuits, miniaturization, precision-guided munitions, and some other systems. NATO's current conventional defense is considered adequate for its mission. But if that mission should be expanded to take over all of the current nuclear role in deterrence, West German officials fear, it could be overloaded.
For all of these reasons Bonn opposes NATO renunciation of any nuclear first use.