length in Thomas Schelling’s 1960 masterpiece, Strate-gy of Conflict (although, as discussed elsewhere in this volume, others had explored some of the ideas previ-ously).16 Schelling observed that, in a crisis, the fear of being empted could itself create pressure to pre-empt. Specifically, because one side’s nuclear weap-ons could destroy an opponent’s, there might be real advantages to landing the first nuclear blow. In con-sequence, two states could be pushed over the brink of war because one state decided the risks of striking
bears emphasizing from the outset that Schelling nev-er argued that such dynamics wnev-ere the only—or even perhaps the main—reason why states would go to nu-clear war. Rather, his point was that if international relations were already severely strained—for what-ever reason—the “reciprocal fear of surprise attack”
might cause them to rupture entirely. Or, as he put it, “[a]rms and military organizations can hardly be considered the exclusively determining factors in in-ternational conflict, but neither can they be considered neutral.”17
Within Schelling’s conception of stability—the
“traditional” conception, if you will—a crisis can be defined as stable if neither side has or perceives an incen-tive to use nuclear weapons first out of the fear that the oth-er side is about to do so. This definition—the one I advo-cate in this chapter—is, in fact, even narrower than the first of Warner’s three definitions (under his definition any first use of a nuclear weapon—whatever the mo-tivation—would be categorized as an instability). By analogy with crisis stability, my preferred definition of arms race stability is the absence of perceived or actu-al incentives to augment a nuclear force—quactu-alitatively or quantitatively—out of the fear that in a crisis an opponent would gain a meaningful advantage by using nuclear weap-ons first.18
The Cold War discourse on stability—crisis stabili-ty in particular—was overly narrow in two important ways. First, concern generally focused on the possi-bility of a state launching a large-scale damage-limit-ing first strike if it believed nuclear war had become imminent. However, such a strike is not the only—or even the most likely—response of a state fearful of an adversary’s using nuclear weapons first. An alterna-tive would be the limited use of nuclear weapons in
an attempt to scare the opponent into backing down.19 This form of crisis instability seems much more likely than a large-scale damage-limiting first strike. Indeed, in a conflict against the United States, only Russia has anything approaching the capability to execute such a strike.
Second, the Cold War literature tended to focus on instabilities arising from the technical characteristics of each side’s strategic forces, that is, on first strike sta-bility. These characteristics (the hardness of silos, the accuracy of missiles, the effect of missile interceptors, and so on) are only some of the factors that would play into a decision to pre-empt. First strike stability is, therefore, a necessary—but not sufficient—condition for crisis stability.20 The sometimes exclusive focus on the technical characteristics of strategic forces arose at least in part because these factors could be easily quantified, whereas other factors relevant to crisis sta-bility—emotion, pressure, bad advice, miscalculation, misperception or poor communication—could not.
During the Cold War, tremendous efforts were put into developing mathematical models for first strike stability. The aim was to quantify the incentives to strike first by modelling a nuclear exchange and using the results to determine whether either side was best served by waiting or attacking.21 These efforts certain-ly had some value; ensuring that vulnerable nuclear forces did not encourage pre-emption was important, and, for that matter, it still is. But, because the mod-els narrowly focused on only some of the potential causes of nuclear war they were, as their developers sometimes acknowledged, limited and they attracted considerable and reasonable criticism. However, a number of contemporary analysts have gone further
the entire concept of strategic stability.22 Such an at-tack is unreasonable; there is a clear difference be-tween the concept of stability and specific, contingent mathematical models that try to quantify it. Using the inadequacies of such models to reject the former is like dismissing the concept of nuclear deterrence out of distaste for the game theoretic analysis that is beloved by a small number of formal deterrence strategists.
This is certainly not to argue that the technical char-acteristics of weapon systems are irrelevant to strate-gic stability. Indeed, the range of relevant systems has broadened as a result of technological change. Early in the Cold War, when stability concerns first emerged, the only plausible “defense” to a nuclear attack was a pre-emptive nuclear first strike. Today, however, there are concerns—particularly among potential U.S.
adversaries—that high-precision conventional weap-ons, including cruise missiles as well as developmen-tal weapons such as “boost-glide” systems, could be used to attack their nuclear forces before launch, while ballistic missile defenses could “mop up” any that survived and were launched. These fears—whether or not they are technically justified—could lead to anxieties about the possibility of a pre-emptive strike during a crisis. A full description of strategic stability in today’s world must, therefore, include convention-al capabilities that could be used to destroy an oppo-nent’s nuclear forces (or its ability to operate them).