The phrase ânuclear threshold â has always referred primarily to that moment in a conflict when nuclear weapons are first used, when a conventional war becomes a nuclear war.1 Beginning with the earliest literature on the advent of nuclear weapons, it was that instant when one side or the other, verging on the precipice of abject military and political collapse and in desperate fear for survival, and having exhausted all other options, commits the âunthinkable,â and introduces nuclear weapons in order to radically alter the calculus of victory and defeat, thus instantly changing the terms of conflict even if it meant placing the future of humanity in jeopardy.2 This literature assumed that this threshold would be crossed only in the midst of a conflict, and it sought to establish the normative conviction that nuclear weapons are somehow special and distinct from âconventionalâ weapons , and their employment must be reserved for only the most dire and catastrophic circumstances, as a last resort. Extensive political, doctrinal, and diplomatic efforts have been engaged to reinforce this distinction, and to perpetuate the presumption against crossing the threshold of nuclear use, a prohibition sometimes referred to as the ânuclear taboo .â3
As nations beyond the United States and the Soviet Union acquired nuclear weapons, the attention of the international community turned increasingly to the task of preventing, slowing, or rolling back horizontal nuclear proliferation , and the phrase took on a second connotation, referring to the decision to acquire nuclear weapons, or at least a nuclear weapons capability.4 As an example of the use of this meaning in a nonproliferation context, Israel was widely assumed to have âcrossed the thresholdâ of nuclear acquisition as early as 1966,5 and successive nuclear tests by India and Pakistan in 1998 were interpreted to mean that those countries had crossed a ânuclear threshold.â More pertinent to the present era, North Koreaâs nuclear tests have decisively established that it too has crossed the threshold of nuclear acquisition. Here the meaning, as indicated by the context, is clearly the acquisition of nuclear weapons capability (demonstrated unambiguously in the case of India, Pakistan, and North Korea through the testing of nuclear devices, more ambiguously in the case of Israel). Nevertheless, now that India, Pakistan, North Korea, and presumably Israel, have crossed the threshold of nuclear acquisition, further discussions of crossing nuclear thresholds in those regions plainly refer to the original meaning of crossing the threshold of nuclear use.6
The existing literature on nuclear decisionmaking has therefore focused largely on this second meaning, the issue of nuclear acquisitionâon what factors contribute to or constrain a nationâs consideration of embarking on a program to acquire nuclear weapons, or, as Jim Walsh phrased it, âthe process tucked between wanting and making a bomb.â7 Yet, the decision to acquire nuclear weapons may not be made in a single moment, and the path to such a decision is replete with other thresholds that must be crossed and re-crossed. The leaders of any given nation in these situations will have to consider crossing or not crossing many key thresholds; whether to develop peaceful nuclear energy capabilities, whether or not to join with the rest of the international community in complying with global nonproliferation norms , whether to establish and operationalize a deployed nuclear deterrent, whether to preemptively counter a regional rivalâs nascent nuclear program, and, possibly in extreme cases, whether to break the taboo against actual use of nuclear weapons and launch a nuclear attack. Each of these thresholds will test a nationâs determination, organizational prowess, and resources. But they will also be manifestations of that nationâs discursive constitution of its own identity , its own values , and its own place in the world of states.
Not only does the context convey the particular connotation meant by the phrase âcrossing the nuclear threshold,â but usage of the two alternate meanings also depends on which community of scholars is employing the term. Understandably, the meaning of threshold as nuclear acquisition is most widely used within the nonproliferation community, while the first meaning described above, to actually use nuclear weapons, is the province of the deterrence and strategic stability communities. In fact, within the nuclear nonproliferation community, a key issue at the foundation of any analysis of nuclear thresholds is the question of what exactly constitutes acquiring a ânuclear weapons capability,â and has been the subject of some dispute. It can mean either when a country has tested a nuclear device, or when it has accumulated sufficient fissile material (or âsignificant quantityâ) through transfer or indigenous manufacture, to assemble a functional nuclear weapon.8
This chapter has five objectives. First, going beyond and supplementing the definitions given above, I introduce additional possible meanings of the concept of âcrossing nuclear thresholds,â that supplement the original notion associated with both the cataclysmic decision to use nuclear weapons and the decision to acquire nuclear weapons. The following chapters further develop these other possible meanings as well, including the threshold of using military force to preemptively counter the prospective nuclear acquisition of a regional rival, the threshold of the âculminating point of deterrence,â and the threshold of deploying operational nuclear weapons capability (often conflated with the nuclear weapons acquisition threshold).
Second, I discuss six types of nuclear thresholds that the authors in this volume have assessed from a sociocultural perspective. The idea and terminology of ânuclear thresholdsâ are central to long-standing debates over the causes of nuclear weapons proliferation, but some of the meanings of these different uses of the phrase âcrossing nuclear thresholdsâ have not been the subject of substantive definitional discourse, and therefore the ways these terms have been used is not always clear or consistent.9 This book is an attempt to provide more explicit definitions and examples for six different potential meanings of the phrase.
Third, I present a preliminary discussion of the notion that identity , values , norms , and perceptual lens can shape and contextualize a given countryâs decisions regarding crossing nuclear thresholds , as will be further developed by the contributing authors. Our approach is intended to employ these four dimensions to craft tailored policy options based upon the cultural profile of a given countryâs nuclear decisionmaking culture.
Fourth, I briefly situate the approach taken by this bookâs editors and authors within the context of other recent literature and concepts that engage and explore ideational factors at play in nuclear decisionmaking .
Fifth, I preview the subsequent chapters and outline the overall structure of the book.
Crossing Nuclear Thresholds
For states pondering their nuclear future, nuclear thresholds can come in many forms. Invariably, the first threshold is acquiring some modicum of nuclear energy producing capability, to generate power or to produce medical isotopes, or to conduct fission experiments. But even this apparently modest threshold poses daunting, time-consuming, and expensive technical, material, experiential, and institutional hurdles. No country that has crossed, or considered crossing, the threshold of nuclear acquisition since the Nuclear Nonproliferation Treaty (NPT) entered into force in 1970, has done so without first building at least a modest civil nuclear power or research infrastructure with the assistance of some other established nuclear power.10 Since Eisenhowerâs âAtoms for Peaceâ initiative in the 1950s, crossing the threshold of civilian nuclear power has had the consensual endorsement and support of the international community, and was enshrined in the NPT as an âinalienable right.â11 It has even taken on the symbology of modernityâit often seems that no country can consider itself truly modern if it has not partaken of the nuclear fruit. And, importantly, for those who chose to pursue this capability under the auspices of membership in the NPT , it has not required violating any international norm , so long as the pursuit of such capability was kept within the regulatory bounds of the international nuclear regime, closely monitored by the International Atomic Energy Agency. Indeed, membership in the NPT brings with it the benefits of technology transfer and assistance, training and experience, a knowledge of safety procedures, and other forms of material and managerial aid.12
So, taking into account our sociocultural focus, I offer this definition of the phrase âcrossing the nuclear thresholdâ: it refers to that point in time where both constitutive sociocultural and political psychological factors converge with objective or structural military, institutional, diplomatic, and economic factors to lead a given state to choose one course of action over another (or, to choose inaction) with respect to its nuclear weapons aspirations. As us...