It has already been more than five decades since the first, and the last, use of nuclear weapons in warfare. Who could have believed it fifty years ago? These five-plus decades of nonuse are a stunning achievement. They may also represent some stunning good luck.

There has never been any doubt about the military effectiveness or the potential for terror of nuclear weapons, and a large part of the credit for their not having been used must be due to the "taboo" that John Foster Dulles, Secretary of State in the Eisenhower administration, perceived to have attached itself to these weapons as early as 1953--a taboo that he deplored.

The weapons remain under a curse, now a much heavier curse than the one that bothered Dulles in the early 1950s. These weapons are unique, and a large part of their uniqueness derives from their being perceived as unique. We call most of the other weapons conventional, in the sense of something that arises as if by compact, by agreement, by convention. It is an established convention that nuclear weapons are different.

This convention, which took root and grew over the past decades, is an asset. It is not guaranteed to survive; some potential possessors of nuclear weapons may not share the convention. How the inhibition arose, whether it was inevitable, whether it was the result of careful design, luck, or both, and whether we should assess it as robust or vulnerable in the coming decades--these are the issues to be examined here.

The first occasion when these weapons might have been used was the Korean War. By September 10, 1950, American and South Korean troops had retreated to a perimeter around the southern coastal city of Pusan and appeared to be in danger of expulsion from the peninsula. The nuclear-weapons issue arose in public discussion in this country and in the British parliament. Prime Minister Clement Attlee flew to Washington to beseech President Truman not to use nuclear weapons in Korea. The visit and its purpose were openly acknowledged. The House of Commons, which viewed its government as having been a partner in the enterprise that produced nuclear weapons, believed that Britain should have a voice in the American decision.

Several days later, a dramatically successful counteroffensive, which began with the landing at Inchon, made moot the question whether nuclear weapons might have been used if the situation in the Pusan perimeter had become desperate. But at least the question of nuclear use had come up. I know of no evidence that apprehension by the government of the United States or by the American public of the consequences of demonstrating that nuclear weapons were "usable" played an important role in Truman's deliberations.

Nuclear weapons again went unused in the debacle following the entry of Chinese armies into Korea, and were still unused during the bloody war of attrition that accompanied the Panmunjom negotiations, which led to the end of the Korean War. Whether the threat of nuclear weapons influenced the truce negotiations remains unclear. But the ambiguity in the "role" of nuclear weapons became evident at that time, and during the ensuing years they clearly remained a threat and a deterrent.

McGeorge Bundy, one of the architects of United States foreign policy in the Kennedy and Johnson administrations, documented the fascinating story of President Eisenhower and Secretary of State Dulles and nuclear weapons in his book Danger and Survival: Choices About the Bomb in the First Fifty Years. At the National Security Council on February 11, 1953, Dulles discussed "the moral problem in the inhibitions on the use of the A-bomb," and it was his opinion that "we should break down this false distinction." Evidently the secretary believed that the restraint was real even if the distinction was false, and that the restraint was not to be welcomed.

Again, on October 7, 1953, Dulles said, "Somehow or other we must manage to remove the taboo from the use of these weapons." Just a few weeks later the President approved, in a Basic National Security Document, the statement, "In the event of hostilities, the United States will consider nuclear weapons to be as available for use as other munitions." This statement surely has to be read as more rhetorical than factual, even if the National Security Council considered itself to constitute "the United States."

Taboos are not easily dispelled by pronouncing them extinct. Six months later, at a restricted NATO meeting, the United States position was that nuclear weapons "must now be treated as in fact having become conventional." But tacit conventions are sometimes harder to destroy than explicit ones, existing in potentially recalcitrant minds rather than on destructible paper.

According to Bundy, the last public statement in this progress of nuclear weapons toward conventional status occurred during the Quemoy crisis, during which the People’s Republic of China repeatedly launched attacks on the island of Quemoy to regain control from Taiwan and the Nationalist forces of Chiang Kai-shek. On March 12, 1955, Eisenhower said, in answer to a question, "In any combat where these things can be used on strictly military targets and for strictly military purposes, I see no reason why they shouldn't be used just exactly as you would use a bullet or anything else."

Was Eisenhower really ready to use nuclear weapons to defend Quemoy, or Taiwan itself? The conspicuous shipment of nuclear artillery to Taiwan was surely intended as a threat. Bluffing would have been risky from Dulles's point of view, and leaving nuclear weapons unused while the Chinese conquered Taiwan would have engraved the taboo in granite.

At the same time, Quemoy would have appeared to Dulles as a superb opportunity to dispel the taboo. Using short-range nuclear weapons in a purely defensive mode, solely against offensive troops, especially at sea or on beachheads devoid of civilians, might have been something that Eisenhower would have been willing to authorize, and nuclear weapons might have proved that they could be used "just exactly as you would use a bullet or anything else." The Chinese did not offer the opportunity.

The contrast between the Eisenhower and the Kennedy-Johnson attitudes toward nuclear weapons is summarized in a public statement of President Johnson's in September 1964:

Make no mistake. There is no such thing as a conventional nuclear weapon. For 19 peril-filled years no nation has loosed the atom against another. To do so now is a political decision of the highest order.

That statement disposed of the notion that nuclear weapons were to be judged by their military effectiveness. Compare "a political decision of the highest order" with "as available for use as other munitions."

Johnson implied that for nineteen years the United States had resisted any temptation to do what Dulles had wanted the United States to be free to do where nuclear weapons were concerned. Johnson implied that we had an investment, accumulated over nineteen years, in the nonuse of nuclear weapons, and that those nineteen years of quarantine were part of what would make any decision to use those weapons a political decision of the highest order.

We should consider the literal meaning of "no such thing as a conventional nuclear weapon." Specifically, why couldn't a nuclear bomb no larger in energy yield than the largest blockbuster of World War II be considered conventional? Two answers were offered to this question, one mainly instinctive and the other somewhat analytical, but both resting on a belief or a feeling--a feeling somewhat beyond reach by analysis--that nuclear weapons are generically different. The more intuitive response could be formulated, "If you have to ask that question you wouldn't understand the answer." The deplorable character of everything nuclear had simply become axiomatic, and analysis was futile.

The other, more analytical, response took its argument from legal reasoning, diplomacy, bargaining theory, and theory of training and discipline, including self-discipline. This argument emphasized bright lines, slippery slopes, well-defined boundaries, and the stuff of which traditions and implicit conventions are made.

The "neutron bomb" is illustrative. The neutron bomb was designed to emit "prompt neutrons" that can be lethal at a distance at which blast and thermal radiation are comparatively moderate. As advertised, it can kill people without great damage to structures. The issue of producing and deploying this kind of weapon arose during the Carter administration, evoking an antinuclear reaction that caused it to be left on the drawing board.

But the same bomb--at least, the same idea--had been the subject of even more intense debate 15 years earlier, and it was then that the arguments were honed before being used again in the 1970s. The arguments were simple, and surely valid, whether or not they deserved to be decisive: (1) that it was important not to blur the distinction--the firebreak, as it was called--between nuclear and conventional weapons; (2) that either because of its low yield or because of its "benign" kind of lethality, there would be a strong temptation to use this weapon where types of nuclear weapons were otherwise not allowed; and (3) that the use of neutron weapons would pave the way for nuclear escalation.

These arguments are not altogether different from those against so-called peaceful nuclear explosions (or PNEs). The decisive argument against PNEs was that they would accustom the world to nuclear explosions, undermining the belief that nuclear explosions were inherently evil and reducing the inhibitions on nuclear weapons. The prospect of blasting new river beds in northern Russia, a bypass canal for the waters of the Nile, or harbors in developing countries generated concern about "legitimizing" nuclear explosions.

A revealing demonstration of this antipathy was in the virtually universal rejection by American arms controllers and energy-policy analysts of the prospect of an ecologically clean source of electrical energy, proposed in the 1970s, that would have detonated tiny "clean" thermonuclear bombs in underground caverns to generate steam. I have seen this idea dismissed without argument, as if the objections were too obvious to require amplification. As far as I could tell, the objection was that even "good" thermonuclear explosions were bad and should be kept that way.

All-or-none thresholds can be susceptible to undermining. A Dulles who wishes the taboo were not there might not only attempt to get around it when using the bomb seems important, but might apply ingenuity to dissolving the barrier on occasions when it might not matter much, in anticipation of later opportunities when the barrier would be a genuine embarrassment. Bundy suggested that in discussing the possibility of using atomic bombs in defense of Dien Bien Phu. (The site of a French military base in North Vietnam, near the border with Laos, in 1954 Dien Bien Phu became the scene of the last great battle between the French and the Viet Minh forces of Ho Chi Minh. After a nearly two-month siege, one in which requests for United States intervention were unheeded, the French positions fell. This defeat signaled the end of French power in Indochina.) In considering the use of atomic bombs to defend Dien Bien Phu, Dulles had in mind not only the local value of such weapons in Indochina but also their broader effect in "making the use of atomic bombs internationally acceptable."

The aversion to nuclear weapons--one might even say the abhorrence of them--can grow in strength and become locked into military doctrine without being fully appreciated or even acknowledged. The Kennedy administration launched an aggressive campaign for conventional defenses in Europe on the ground that nuclear weapons certainly should not be used, and probably would not be used, in the event of a war in Europe. Throughout the 1960s the official Soviet line was to deny the possibility of a non-nuclear engagement in Europe. Yet the Soviets spent great amounts of money developing non-nuclear capabilities in Europe, especially aircraft capable of delivering conventional bombs. This expensive capability would have been of limited value in a nuclear engagement. Deployment of these weapons reflected a tacit Soviet acknowledgment that both sides might be capable of non-nuclear war and that both sides had an interest in keeping war non-nuclear by having the capability of fighting a non-nuclear war.

Arms control is so often identified with limitations on the possession or deployment of weapons that people often overlook the fact that an investment in nonnuclear weapons constitutes a form of arms control. That the Soviets had absorbed this nuclear inhibition was dramatically demonstrated during their protracted campaign in Afghanistan. I never read or heard public discussion about the possibility that the Soviet Union might shatter the tradition of nonuse to avoid a costly and humiliating defeat in that primitive country. The inhibitions on use of nuclear weapons are such common knowledge, the attitude is so confidently shared, that the use of nuclear weapons in Afghanistan would have been almost universally deplored.

Such a reaction would reflect appreciation that Washington's nineteen-year nuclear silence had stretched into a fourth and then a fifth decade, and everyone in responsibility was aware that that unbroken tradition was a treasure we held in common. Could that tradition, once broken, have mended itself? If Truman had used nuclear weapons during the Chinese onslaught in Korea, would Johnson have been so inhibited in 1964? And if Nixon had used nuclear weapons, even ever so sparingly, in Vietnam, would the Soviets have eschewed their use in Afghanistan, and would the Israelis have resisted the temptation of use against the Egyptian beachheads north of the Suez Canal in 1973?

We do not know. One possibility is that the horror of Hiroshima and Nagasaki would have repeated itself, and the curse would have descended again with even more weight. The other possibility is that, the long silence broken, nuclear weapons would have emerged as standard weaponry against an adversary who had none. Much might have depended on the care with which weapons were confined to military targets or used in demonstrably "defensive" modes.

I have devoted this much attention to the nuclear taboo in the belief that the evolution of that status has been as important as the development of nuclear arsenals. The nonproliferation effort has been more successful than most authorities can claim to have anticipated; the accumulating weight of tradition against nuclear use is no less impressive and no less valuable. We depend on nonproliferation efforts to restrain the production and deployment of weapons by more and more countries; we may depend even more on universally shared inhibitions on nuclear use. Preserving those inhibitions and extending them, if we know how, to cultures and national interests that may not currently share those inhibitions will be a crucial part of our nuclear policy.

On the 40th anniversary of Hiroshima and Nagasaki, Alvin M. Weinberg wrote an editorial in the Bulletin of Atomic Scientists (December 1985). In 1941, Weinberg had joined the University of Chicago group that developed the first chain reactor which produced the plutonium ultimately used in the atomic bomb dropped on Nagaski. In his editorial, Weinberg expressed his conviction that both American and Japanese lives were saved by the use of the bomb in Japan, and that long-term good might result from the Hiroshima bomb:

Are we witnessing a gradual sanctification of Hiroshima--that is, the elevation of the Hiroshima event to the status of a profoundly mystical event, an event ultimately of the same religious force as biblical events? I cannot prove it, but I am convinced that the 40th Anniversary of Hiroshima, with its vast outpouring of concern, its huge demonstrations, its wide media coverage, bears resemblance to the observance of major religious holidays.... This sanctification of Hiroshima is one of the most hopeful developments of the nuclear era.

A crucial question is whether the antinuclear instinct so well expressed by Weinberg is confined to Christian or "Western" culture. As we look to North Korea, Pakistan, Iran, India, or Iraq as potential wielders of nuclear weapons, we cannot be sure that they inherit this tradition with any great force.

Forty years ago, however, we might have thought that the Soviet leadership would be immune to the spirit of Hiroshima as expressed by Weinberg--immune to the popular revulsion toward nuclear weapons, immune to the overhang of all those peril-filled years that awed President Johnson. In any attempt to extrapolate Western nuclear attitudes toward the areas of the world where nuclear proliferation begins to frighten us, the remarkable conformity of Soviet and Western ideology is a reassuring point of departure.

I know of no argument in favor of the Comprehensive Test Ban Treaty, which the Senate rejected in 1999, more powerful than the potential of that treaty to enhance the nearly universal revulsion against nuclear weapons. The symbolic effect of 140 or more nations ratifying this treaty, which is nominally only about testing, would add enormously to the convention that nuclear weapons are not to be used, and that any nation that does use nuclear weapons will be judged the violator of the legacy of Hiroshima. I have never heard that argument made on either side of the debate over the treaty. When the treaty again comes before the Senate, as it certainly will do, this major potential benefit must not go unrecognized.

Thomas C. Schelling
Distinguished University Professor
School of Public Affairs
4109 Van Munching Hall
University of Maryland
College Park, Maryland 20742-2711
ts57@umail.umd.edu