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Library of Congress Cataloging-in-Publication Data
Names: Koch, Lisa (Lisa Langdon), author.
Title: Nuclear decisions : changing the course of nuclear weapons programs / Lisa Langdon Koch.
Description: New York, NY : Oxford University Press, [2023] | Includes bibliographical references and index.
Identifiers: LCCN 2022062279 (print) | LCCN 2022062280 (ebook) | ISBN 9780197679531 (hardback) | ISBN 9780197679548 (epub) | ISBN 9780197679555 | ISBN 9780197679562
LC record available at https://lccn.loc.gov/2022062279
LC ebook record available at https://lccn.loc.gov/2022062280
DOI: 10.1093/oso/9780197679531.001.0001
Contents
Acknowledgments
1. Introduction to Nuclear Decisions
2. Proliferation Curves
3. A Theory of Nuclear Decision-Making
4. Changing Proliferation Environments across the Nuclear Age
5. The Permissive Period: The Soviet Union, Israel, and France
6. The Transition Period: Sweden, South Korea, and India
7. The Nonproliferation Regime Period: Pakistan, South Africa, and Brazil
8. Changing the Course of Nuclear Weapons Programs
Appendix
Notes
Bibliography
Index
Acknowledgments
I began conducting the research that led to this book when I was a graduate student at the University of Michigan. Allan Stam supported and encouraged my work, helped me think about the big picture, and never failed to provide wise counsel. James Morrow, Philip Potter, and Robert Franseze each taught and advised me in important ways as I pursued this research in its early form and in the years after I finished my graduate work. I remember in particular the times I was lucky enough to be able to talk about the project with Al, Jim, Phil, and Rob all together, and I thank them for their invaluable insights and advice. I am also grateful for Charles Shipan’s scholarly guidance, and for his continuing mentorship. Chuck’s graduate seminar on American political institutions influenced the way I think about key institutional players and the relationships among them. I thank Cameron Thies, Thorin Wright, and many other generous scholars at the School of Politics and Global Studies at Arizona State University for their support and assistance as I finished my dissertation.
I am indebted to Scott Sagan, Vipin Narang, and Branislav Slantchev, whose insights shaped my thinking about the manuscript. I reflected upon our lively discussion many times when making the revisions that have led to a better book. I thank Scott in particular for his mentorship, which began several years ago when I introduced myself after a conference panel. Scott invited me to sit down then and there to tell him about my work, and I have benefited from his generous guidance and insightful critiques ever since.
My colleagues at Claremont McKenna College made the development and completion of this book possible in many different ways. I thank Hilary Appel and the Keck Center for Strategic and
International Studies for supporting the development of the manuscript at key moments. The Government Department has enthusiastically supported my research since I arrived at CMC, and I thank especially Hilary Appel, William Ascher, Mark Blitz, Hicham Bou Nassif, Jordan Branch, Andrew Busch, Roderic Camp, Minxin Pei, Jack Pitney, Shanna Rose, Jon Shields, Aseema Sinha, Jennifer Taw, and George Thomas for their insights and advice. When I arrived at CMC, I had the good fortune to be assigned the office next to the other assistant professor in the department, Emily Pears. I thank Emily for her friendship, for many conversations about the process of writing a book, and for helping me think through theoretical tangles that arose as I wrote.
For generating and sustaining a faculty writing community, I am grateful in particular to Peter Uvin, Adrienne Martin, Esther ChungKim, Ellen Rentz, Sharda Umanath, Heather Ferguson, Emily Pears, and Janice Heitkamp. I thank the outstanding students who provided excellent research assistance, including Katrina Frei-Herrmann, Daniel Krasemann, Tallan Donine, Marcia Yang, Alexander Li, Johnson Lin, Charles Warren, and my many nuclear politics seminar students, in particular Henrietta Toivanen and Stuart Brown. Katrina deserves special recognition for working with me on various projects over three years and for executing the first polished drawings of the proliferation curves.
Alexander Lanoszka, Sarah Croco, Matthew Fuhrmann, and Leanne Powner each offered valuable advice during the writing process. I thank Matthew Wells for many discussions and conversations as the project evolved, and most of all for many years of friendship. At the University of Michigan, I relied on the professional knowledge and experience of political science librarian Catherine Morse, and on Sofia Rosenberg, who volunteered to translate Swedish writings into English so that I could puzzle out the characteristics of Swedish nuclear institutions. I thank David McBride and two anonymous reviewers for Oxford University Press for their valuable guidance, and Sharon Langworthy for expert copyediting.
I am indebted to Donald Hafner, who taught me about nuclear weapons strategy when I was an undergraduate student at Boston
College. His teaching and his ideals continue to inspire me, and I greatly value his ongoing mentorship. For their scholarly advice and their friendship, I thank Katja Favretto, Vanessa Cruz-Nichols, and Ida Salusky. I thank Rebecca Martinez for significantly influencing my approach to the process of research and writing. I am grateful to my faith community at the Claremont Colleges, in particular Steve Davis, Esther Chung-Kim, TJ Tsai, George Montanez, and Dave Vosburg for steadfast support.
My family deserves the most thanks, starting with my mom and dad, Janice and John Langdon, and my sister, Heather, each of whom has always provided me with unconditional love and support. From the start, they have been enthusiastic about this project and its development into a manuscript, and I am deeply grateful for our many conversations and for their advice. My mother-in-law and father-in-law, Paige and Joseph Koch, have also showered me with love and support ever since I had the good fortune to join their family. They have read my work, sent me articles related to my research, and thoughtfully asked me about the manuscript’s progress.
My dad is professor emeritus of history at Le Moyne College, and I thank him in particular for the many, many hours he has spent reading and commenting on various drafts of this manuscript over the years. Everyone should be so lucky as to have a world historian on call while conducting case research, not least because the conversations are such great fun.
I completed much of this manuscript in 2020 and 2021, during the global pandemic. My husband, Matt, and I worked hard to try to adapt to a time of significant disruption, including the loss of inperson school for our three children for more than a year. Writing during this time was tremendously challenging, and I am truly fortunate to be part of a wonderful family of five that sustains me. Thank you, Matt, for your love and support over many years. You have been on the entire journey with me, start to finish. And finally, I thank our children, Audrey, Paul, and Timmy, who sometimes permit me to sneak in a few more minutes to write, sometimes distract me, and always fill our lives with a special joy.
1
Introduction to Nuclear Decisions
The pursuit of nuclear weapons is rarely the story of a race to the bomb at any cost. Even the five initial nuclear pursuers, each of which worked to acquire nuclear weapons in the context of World War II, did not take uniform paths. The United States devoted vast national resources to developing a fission bomb as quickly as possible, and the British government provided expert and material support to that project.1 The Soviet Union, Germany, and Japan made different decisions, however, resulting in different approaches to nuclear weapons development. Those nuclear decisions shaped not only the outcome of the atomic programs but also, quite possibly, of the war itself.
Japan offers an interesting example. Japan’s uneven efforts to develop nuclear weapons were initiated by Army Minister Tōjō Hideki in 1940, well before the United States launched the Manhattan Project. Most Japanese officials remained unconvinced that atomic bomb research and development should be prioritized, and the poorly funded program made slow and unsteady progress.2 However, in October 1941 Tōjō ascended to the office of prime minister. After Japan’s 1942 loss at Midway, Tōjō led the cabinet to accelerate new weapons development, including the nuclear bomb projects.3
Despite the enormously high stakes for Japan, the effort, shaped by leaders’ decisions, did not succeed. While the American nuclear weapons project took the form of a single, focused effort, under Japan’s highly militarized government, different service branches conducted separate, fragmented nuclear programs.4 As Manhattan
Project scientists made swift progress toward a nuclear test in New Mexico, Japanese scientists advised military officers that atomic weapons would take too long to build and declared that American scientists surely faced the same constraints and difficulties. Within one of the navy’s nuclear projects, the frustrated captain in charge had first told the scientists to redouble their efforts. But eventually he too abandoned the nuclear project in favor of other, wellestablished research and development programs that were making better progress. Scientists’ pessimistic reports continued to inform decision-making, and in June 1945—less than a month before the United States would successfully test its first nuclear device—Army Minister Anami Korechika decided to shut down the army’s nuclear program. The navy terminated a second nuclear project in July 1945.5
On August 6, 1945, the United States attacked the Japanese city of Hiroshima with the first nuclear weapon used in war. In the immediate aftermath, some leaders, including the emperor, recognized the likely implications. But the failure of Japan’s nuclear weapons effort, and the scientists’ belief that no other country could succeed where Japan had failed, injected confusion and doubt into official discussions. The army rejected the possibility of an American atomic bomb, branding as propaganda President Harry S. Truman’s post-attack announcement to the world. And the few military officers who were willing to accept that the United States had produced one atomic bomb assumed the Americans lacked the capacity to quickly produce more. Japan’s military elected to proceed with existing plans to defend Japan from invasion.6
In contrast, Soviet leaders already knew that the US atomic effort had succeeded and correctly interpreted the news from Hiroshima.7 Having previously agreed to attack Japan no later than August 15, and realizing that the atomic bomb would change the course of the war’s conclusion, the Soviet Union launched a million-soldier attack against Japanese troops in Manchuria on August 9, broadcasting the declaration of war on Moscow Radio a day earlier. The forceful denials and expressions of doubt from Japan’s scientific and military
experts, which arose from their frustrations with the nuclear project and the decisions to abandon the work, had delayed Japan’s response to the bombing of Hiroshima. Now, reeling from the additional shock of the Soviet attack, Japan’s Supreme War Council met in a bomb shelter beneath the imperial palace and began at last to discuss surrender with new urgency.8
Despite the common context of World War II, Japan’s nuclear development looked very different from America’s, and different still from the Soviet Union’s. As today’s nuclear hopefuls work toward acquiring nuclear arsenals, their programs, too, have taken paths that have been difficult to predict. Approximately two dozen states have decided, at some point, to pursue the bomb. Yet throughout the nuclear age, the progress states have made toward that goal has been neither linear nor consistent. Why does the pursuit of nuclear weapons look so different across cases? How can we make sense of the range of paths to and away from the bomb?
Nuclear Decisions
Nuclear decisions offer the answer. State leaders make decisions within different information environments that affect their beliefs and preferences about nuclear weapons. These decisions to accelerate or reverse progress toward a nuclear weapons capability define each state’s course. Whether or not a state ultimately acquires nuclear weapons depends to a large extent on those nuclear decisions.
I argue that two crucial features of the political environment affect nuclear decision-making. Leaders make decisions not in a vacuum but in changing international and domestic contexts. First, in different proliferation eras, changes to international political and structural conditions constrain or free states to pursue nuclear weapons development. These conditions are imposed from the top down. Second, across these eras, domestic scientific and military organizations may intervene to bring about, or prevent, a nuclear decision that could redefine a state’s course to the bomb. The conditions under which scientific and military experts are able to
influence state leaders from the bottom up are thus a critically important aspect of this story.
Nuclear Goals
The historical record demonstrates that states do not initiate nuclear weapons programs and then uniformly follow linear paths to a singular goal. One possible explanation for erratic progression is political meddling in scientific research and development. Jacques E. C. Hymans argues that leaders who are unconstrained by state institutions often interfere in nuclear weapons programs, unintentionally disrupting progress toward the bomb. Whether scientists are free to pursue their work in ways that will advance good research and development or instead face strong incentives to appease repressive leaders through shortcuts and false reporting should affect a program’s timeline.9
This compelling argument about time-to-outcome, however, cannot explain the form a nuclear weapons program takes. Implicit in Hymans’s argument are the assumptions that states have a common goal—to quickly produce nuclear weapons—and take linear paths to the bomb. The observation that few states had obtained a speedy outcome led Hymans to conclude that something had gone wrong. However, while racing to the bomb was more common during the early Cold War, for most of the nuclear age the full-speed-ahead approach has been the exception, not the rule.10 Rather, leaders have exhibited a range of preferences regarding the importance and necessity of quickly acquiring a nuclear arsenal.
If these nonlinear pathways are not a deviation—if nuclear weapons development is instead typically nonlinear—then interference with project management cannot be a sufficient explanation. I argue that the paths to the bomb are rarely linear because they are interrupted and reformed by nuclear decisions. Leaders may allow a nuclear weapons program to maintain the course it is on or even decide to slow or suspend its development. Domestic organizations are a key source of expert information that
shapes the leader’s perception of the value and strategic purpose of the nuclear program.
Another possible explanation is that changes in the security environment prompt a state to move toward or away from the bomb. Security concerns are an important motivator for the initial decision to start a nuclear weapons program.11 Yet the security explanation, too, is insufficient. States that do decide to begin a program may exist in insecurity for years before choosing the nuclear path. And once a nuclear weapons program is underway, many leaders appear to make nuclear decisions that are not based on either stable or changing external security environments. If security were the sole driver of nuclear decisions, we would expect to see acceleration decisions during times of high insecurity and reversal decisions during times of low insecurity.
The case studies I conduct in this book do not indicate the presence of such a dynamic. For example, India’s program slowed significantly in the mid- to late 1970s, despite nuclear weapons progress in its regional rivals, China and Pakistan. South Korea did not accelerate its program when its security environment worsened. Brazil gave up its pursuit of nuclear weapons despite little to no change in its security environment. South Africa sprinted toward a nuclear arsenal despite its significant regional military superiority. Perhaps deep concerns over Soviet interference in southern Africa, or even fears of invasion, could explain South Africa’s proliferation curve instead—but then why did Pretoria implement two different program reversals, well before the fall of the Soviet Union?12
Within the context of an ongoing nuclear weapons program, the threat environment is not the only important factor that affects leaders’ perceptions of the costs and benefits of the nuclear weapons effort. A nuclear weapons program is one of many options available to a government that faces serious security concerns. A state could instead decide to arm conventionally, seek military assistance from an ally, or enter into a defense pact. Or a leader may decide to gain leverage over adversaries by hedging: pursuing nuclear development to achieve a latent nuclear weapons capability
without progressing all the way to the weapons themselves. Fears of a preventive war aimed at the nuclear program could prompt either a reversal decision to remove the cause of the threat or an acceleration decision, in hopes of acquiring nuclear weapons to deter future attack. A threatening security environment could therefore lead to either type of decision or no decision at all. Security cannot fully explain states’ proliferation pathways.
Because states consider different policy options in response to the strategic environment, and each option has its own potential benefits and drawbacks, nuclear weapons programs are situated within a political context. Leaders consider many possibilities beyond the simple binary outcomes of acquisition or termination, and they do so within a complex information environment that affects how the value of a nuclear weapons program is understood. They must weigh the benefits of state security against drawbacks like domestic resource trade-offs, potential damage to strategic international relationships, and the likelihood of program success.
Decisions Define Programs
My approach jettisons the assumption that leaders in nuclear weapons–pursuing states share a common desire to acquire nuclear weapons as quickly as possible. Instead, I hold that leaders make political decisions to accelerate, slow, or end altogether the path of nuclear weapons development. I offer a novel theory of nuclear decision-making that identifies two mechanisms that shape leaders’ understandings of their nuclear pursuits. The external mechanism— the proliferation constraints that emerge from the structure and politics of the international system—has evolved across three distinct time periods, which I define and describe in Chapter 4.
The internal mechanism is the intervention of domestic experts, which I briefly introduce in the next section. Leaders make decisions in an informational environment that, under the right circumstances, experts may be able to structure. I examine the conditions under which scientific and military organizations are able to influence state leaders from the bottom up. In conducting a systematic examination
of proliferators extending beyond the United States, I obtain a broad range of evidence to support my arguments. Through this approach to studying nuclear proliferation, I find something very different than the conventional wisdom. Determined states do not simply pursue a straight path to nuclear weapons acquisition. Nuclear decisions define a state’s nuclear pursuits.
The Domestic Nuclear Decision-Making Environment
The internal mechanism of domestic expert influence has been present from the start of the nuclear weapons age. There were many reasons that Japanese and American leaders made such different nuclear decisions in the 1940s. The practicalities of waging war and the outcomes of battles created different constraints on each country’s national resources and capabilities. But from the start American and Japanese leaders also operated in different information environments. They made important decisions about whether, and how, to continue along the path to the bomb, and each did so within a political context that was shaped not only by the external security environment but also by key domestic organizations that house nuclear experts.
I argue that the key domestic organizations that hold distinct preferences about nuclear weapons are the domestic nuclear agency and the state military. These organizations are important sources of information and incentives that can, under certain conditions, influence a leader’s beliefs about the value of a nuclear weapons program relative to the cost. They are not the sole influencers of leaders’ strategic calculations, nor can they explain every case of nuclear decision-making. But they are a crucial source of information and influence in the nuclear context.
Further, nuclear agencies and militaries may take advantage of opportunities to shape leaders’ knowledge and understanding of the domestic and international factors that affect nuclear decisionmaking. An organization with greater access to and influence over
the leader has greater capacity to inform and persuade. Effective organizations can alter the leader’s perceptions of the costs and benefits of pursuing nuclear weapons and may work to constrain or expand the set of options the leader will choose among. In addition, nuclear agencies and militaries have heightened abilities to influence leaders on nuclear weapons matters because leaders typically assume office without a background in nuclear science or doctrine. The secretive and technologically sophisticated nature of nuclear weapons development renders these programs largely opaque to state leaders, who then rely on these key organizations to signal the benefits and disadvantages of the nuclear weapons effort.
Within domestic nuclear agencies, nuclear scientists are professionally invested in nuclear development and prefer to push programs forward. Nuclear agencies also enjoy an informational advantage because states do not employ rigorous oversight of the highly secret, expert processes of designing, producing, and testing nuclear weapons. I argue that more independent nuclear agencies, with greater access to political leadership, are better able to control the flow of information on nuclear benefits and to exert influence on decision-makers both to accelerate programs and to prevent reversals.
Military organizations, on the other hand, may be less likely to advocate for nuclear acceleration during development stages and more likely to allocate resources to conventional capabilities instead. Competing organizational interests may lead a military to prioritize spending on conventional arms, which provide immediate utility, rather than on the long-term potential of developing a future nuclear capability. While militaries value the deterrent benefits of nuclear weapons, they also believe that future wars are more likely to remain conventional. Many within the military will prefer to invest organizational resources in the conventional weapons and equipment most likely to be used in war fighting. When a military organization leads the government, the leader will need to satisfy traditional military interests to remain in office and will be likely to seek to use conventional means to conduct political repression and consolidate power.
Each of these organizations may—or may not—be able to shape the country leader’s understanding of the domestic and international factors that affect nuclear decision-making. An organization with greater access to and influence over the leader has a greater opportunity to inform and persuade. Effective organizations can alter the leader’s perceptions of the costs and benefits of pursuing nuclear weapons and may work to constrain or expand the set of options the leader will choose among. But organizations that lack access to the leader, or that lack the capacity to advance their interests, are unlikely to have a significant effect on nuclear decision-making.
Implications
This book joins the growing literature on nuclear proliferation and reversal, offering a systematic analysis of the process and politics of nuclear decision-making. I approach this subject from a different conceptualization of nuclear weapons programs: that they are defined by decisions to accelerate or reverse nuclear development. In doing so, I investigate the strategic decisions that create the form of nuclear weapons programs rather than focusing on the time between program initiation and the outcome of a nuclear bomb. Pursuing nuclear weapons, whether in Iran, North Korea, India, or Pakistan, is a long process punctuated by political decisions that can change the course of nuclear development. Rather than examining the conditions present when a milestone program outcome is realized, I examine the conditions present at the time the nuclear decision was made.
This analysis reveals that both international structural conditions and domestic coalitions matter. Even in wartime, whose voices are heard from within the state and what preferences they express can change how a leader understands the international environment. Those domestic experts can highlight or downplay the advantages and disadvantages of steps to change the course of nuclear weapons development. The relative balance of power among the key domestic organizations, which can change as they interact with each other
and their political environment, affects the ability each expert group has to influence the leader. These organizations may prefer to push the state either toward or away from nuclear weapons. If we ignore the domestic environment and instead assume that states pursue nuclear weapons along uniform and consistent paths, we underestimate the importance of the nuclear decisions that determine whether a state ultimately acquires nuclear weapons.
Finally, a central argument of this book is that we should not study the decision to start a nuclear weapons program as if the state’s ultimate goal is to quickly produce the weapons. Not only do nuclear aspirants pursue different goals, but changing circumstances may also lead a state to later deviate from the original goal. And because the end results of nuclear decisions are realized months or years later, programs may reach milestones that are the product of decisions made by leaders who were responding to conditions that have since changed. Because a nuclear weapons program outcome will occur at some period of time after a nuclear decision was made, examining the conditions at the time of the outcome will be misleading. We should instead seek to understand the conditions at the time of the decision that paved the way to the outcome. This shift in focus could allow states to respond more productively to changes in their adversaries’ or allies’ nuclear weapons development and create better nonproliferation policy tools.
Plan of the Book
The book begins with the theoretical argument. Leaders are at the center of nuclear decision-making, but they face serious constraints on their access to, and understanding of, the range of possible nuclear choices and outcomes. I present evidence of the different proliferation pathways and define nuclear decision-making in Chapter 2. In Chapter 3 I discuss how, and when, nuclear agencies and military organizations influence leaders’ decision-making, as well as why alternative explanations are insufficient. In Chapter 4 I describe the features of each of the three historical eras I have
defined, and I explain why each era comprises a distinct decisionmaking context in which states operate over time.
In Chapters 5, 6, and 7 I test my arguments through case studies of countries that have pursued nuclear weapons. The three chapters, each of which contains three different country studies, correspond to the three historical eras. In organizing the cases by era, I am able to examine how nuclear decision-making has been conducted within each international context.
The case study approach provides the benefit of adding context and depth to broad theorizing. One could argue that certain decisions seem to have been brought about by very specific causes, or that each decision may be situated in a unique historical and cultural context. I do not claim that the theory I present wholly explains every nuclear weapons program decision. While it is true that some decisions may be exceptional, developing a theory of decision-making is an exercise in seeking out common factors that systematically affect the likelihood of a decision being made. Case studies allow me to explore these dynamics and attempt to illustrate common mechanisms that underlie nuclear decision-making. Finally, in Chapter 8 I discuss nuclear decision-making in the current case of Iran and explore the implications of this study for nonproliferation policy.
2
Proliferation Curves
Much of the literature on the pursuit of nuclear weapons concerns the decision to start a program or the conditions under which states succeed in acquiring nuclear arsenals. While weapons acquisition is an outcome rather than a decision, systematic studies typically blur the distinction between the two events. Several studies first estimate a model of nuclear start decisions and then re-estimate the model with a new dependent variable: the year of nuclear weapons acquisition. But uneven findings across these studies warn against conflating decisions (program start) and outcomes (weapons acquisition).1 Considering the two different types of events—a decision and an outcome—within one common framework has not generated a coherent theoretical explanation. This should not be surprising given the conceptual muddling of a political decision and an end product that is many steps removed from that initial decision.
In this chapter I demonstrate that nuclear proliferation should instead be conceived of as a political process that hinges on decisions. I identify types of nuclear decisions and then present empirical evidence of the proliferation pathways—which I call proliferation curves—taken by six nuclear weapons pursuers. The proliferation curves indicate that leaders do not pursue nuclear weapons in uniform ways. At first glance, nuclear decisions do not appear to be easily predictable.
The Path to the Bomb
From the start, nuclear decisions have been political decisions. In August 1939, as top scientists around the world conducted theoretical work on nuclear fission, then on the cutting edge of physics, Albert Einstein drafted a letter to President Franklin D. Roosevelt. Many scientists already understood that the enormous energy produced by splitting uranium nuclei could be used in war. In his letter to Roosevelt, Einstein explained the potential for the development of “extremely powerful bombs of a new type” and speculated that Germany’s capture of Czechoslovakian uranium mines indicated that Hitler was already pursuing a fission bomb.2
Einstein’s letter established an informational context for Roosevelt that affected how he interpreted new, related information. The United States did not establish a nuclear weapons program until October 1941. But Richard Rhodes explains how, when news of Britain’s successful progress toward a fission bomb finally reached the president, Roosevelt understood that using nuclear energy for military purposes had the potential to “change the political organization of the world.”3 He had listened to his advisers describe the decisive power expected from these astonishingly destructive weapons, and he had considered the long-term, strategic impact of nuclear bombs.4
Roosevelt’s early intuition that nuclear weapons would reshape the world order has been affirmed by the governments that have attempted, at great expense, to develop their own nuclear arsenals.
Acquiring nuclear weapons is a feat that may redefine a state’s position in the international system, establish a new context for the state’s relationships with allies and adversaries, and mark that state as an advanced technological and scientific power. Unsurprisingly, then, because nuclear weapons are so strongly linked to state interests, decisions about nuclear weapons program development are made at the highest levels of government.
Nuclear Acceleration and Reversal Decisions
Once a government has begun a nuclear weapons program, subsequent decisions may be made to accelerate or reverse the program. Because these decisions are deeply political, involving entrenched and often competing interests, they may be debated by political officials, military elites, and nuclear scientists at high levels of government. Ultimately, however, significant decisions about the course of a nuclear weapons program are political ones made by the country’s leader.5
I sort nuclear decisions into two broad categories: those that are intended to accelerate a nuclear weapons program and those that are intended to reverse it. While little scholarly attention has been paid to systematically examining acceleration across cases, country studies and a few cross-national studies have contributed a great deal to our understanding of nuclear reversal. I follow Ariel Levite in defining nuclear reversal as a governmental decision to significantly slow, or suspend, a nuclear weapons program. Rupal Mehta also incorporates Levite’s definition in her study of nuclear reversal, allowing for the possibility that a reversing state may later restart its program after a freeze.6 A reversal decision may lead to a range of different outcomes on various timelines that may only be observable years later.
Using the same logic, I define nuclear acceleration as a governmental decision to significantly speed up an existing nuclear weapons program. In Table 2.1 I provide a range of nuclear acceleration and reversal decisions that leaders have made in the course of pursuing nuclear weapons. Each of these decisions significantly contributes to a state’s progress toward or away from nuclear development and represents another piece of the proliferation puzzle.
Table 2.1 Types of Nuclear Decisions
Acceleration Decisions Reversal Decisions
Deciding to invest significant resources in the nuclear weapons program; for example, creating or significantly expanding research and education institutions
Moving from research and development to building enrichment or reprocessing facilities
Reviving a suspended program or restarting an enrichment or reprocessing facility
Initiating a crash program to acquire nuclear weapons on a short timetable
Moving from trying to acquire offthe-shelf nuclear weapons to trying to build an indigenous capacity
Deciding to move from latent nuclear weapons capacity to building a bomb
Deciding to develop thermonuclear (hydrogen) weapons
Deciding to develop deliverable nuclear weapons
Shifting military expenditures and priorities from nuclear to conventional weapons programs
Suspending militarized nuclear research, including continuing the research program but limiting its scope to civilian nuclear energy
Making significant budget or resource reductions to the nuclear weapons program
Delaying or suspending work on enrichment or reprocessing facilities
Delaying or suspending work on militarized components of the nuclear program, such preparing a testing site
Moving from trying to build an indigenous capacity to acquiring offthe-shelf nuclear weapons
Deciding not to proceed with building nuclear weapons despite being capable of doing so
Suspending production of nuclear weapons or related materials
Ending a militarized nuclear program by giving up nuclear equipment/technology to a foreign state
Dismantling an existing nuclear arsenal
A nuclear decision can bring about a temporary acceleration or deceleration in program development, or it can have more permanent effects. States making the decision to reverse may later decide to accelerate a slowed program or revive a suspended program; this has happened, for instance, in Iran, North Korea, India, Taiwan, the former Yugoslavia, and Pakistan. Other states,
after a reversal decision, may continue to make additional reversal decisions and may ultimately decide to end their nuclear weapons programs; examples include Brazil, Australia, Sweden, South Africa, and Switzerland.7
Different types of nuclear decisions may be made for different strategic reasons. A program may be suspended because the leader has come to question the value of the nuclear weapons program, but suspension may also be a tactical move made to gain concessions through an agreement with a foreign partner. The reasons for a reversal decision are important but may not be known or understood by outside observers, or even regime insiders, not only at the time of the decision but also for many years afterward. But whether the reversal decision was made because the government doubts that nuclear weapons acquisition is still in the interests of the state, or because the government plans to extract side payments in the present and then restart the program if it becomes advantageous in the future, that decision still affects the state’s course of nuclear development. In either case, reversal slows the momentum of the nuclear program and adds months or years to the acquisition timeline.
Both types of reversals could also later be reversed by nuclear acceleration decisions.8 A reversal decision made to fulfill the terms of an international agreement is vulnerable if the agreement fails or if there is a change in the conditions that facilitated the parties’ willingness to negotiate. But a reversal decision made by a leader who is losing interest in the nuclear project may also be impermanent. Either the same leader or a successor could be persuaded to reinvest in a slowed or suspended program, as occurred twice in the Indian case. Neither type of reversal is irreversible, and both types affect the course, and future outcomes, of a nuclear weapons program.
Acceleration decision-making has gone virtually unanalyzed, other than within individual country case studies. The study of nuclear reversal has obvious policy implications, as a better understanding of the conditions under which reversal occurs may aid states in slowing
the spread of nuclear weapons. However, understanding the conditions under which acceleration is likely to occur also contributes to nonproliferation efforts. This is particularly true because acceleration decisions, which initiate long-term, costly investments and do not generate immediate, usable results, are not necessarily made in direct response to external threats to a state’s security. When a leader decides to accelerate a nuclear weapons program, the intended outcome of the acceleration may not be realized for months or years. As accelerating a program constitutes a long-term investment rather than a rapid response, it is unlikely that leaders would routinely react to sudden changes in the threat environment by making nuclear acceleration decisions.
Just as I classify reversals by the decision to reverse rather than by the eventual outcome, I examine acceleration by identifying decisions to speed up nuclear development rather than by the eventual outcome of nuclear weapons acquisition. An acceleration decision may quickly result in the production of nuclear weapons, or it may not.9 But if outcomes are the variable of interest, a subsequent decision to reverse a nuclear program would hide the acceleration decision from view. Studies that limit analysis to outcomes, or that define reversal only as termination, omit these program changes. Such analyses are incomplete at best and biased at worst.
Proliferation Curves
If nuclear decisions shape states’ proliferation pathways, what do different paths to and away from the bomb look like? In the following discussion I represent six states’ paths, or proliferation curves, with basic graphs. Along the proliferation curve, nuclear decisions are represented by vertical lines, each appearing during the year the decision was made. Dashed lines represent a nuclear reversal decision, with double-dashed lines representing a permanent reversal decision. A solid line indicates a nuclear acceleration decision. Each graph measures time in years along the
x-axis and nuclear development milestones along the y-axis. The data I used to generate each proliferation curve, and the sources I relied on, are reported in the appendix.
The milestones I have selected for these graphs indicate key stages of nuclear development. As a state progresses toward, or away from, nuclear weapons, the proliferation curve travels through these different stages. States establish a research and development program, obtain uranium or plutonium, build a nuclear reactor, operate the reactor, enrich fissile material so it can be used in a bomb, test a bomb, and develop delivery systems. It is not always obvious when a state moves from one milestone to the next, in part because these accomplishments are often closely guarded secrets. The dates and milestones I use in these graphs are accurate to the best of my knowledge as of this writing. Furthermore, the progression along the path of nuclear weapons development is not always linear. Different decisions made in the course of a program have caused some states to skip over a milestone, such as accumulating a stockpile of nuclear weapons and developing delivery systems before testing a prototype bomb. A black diamond marks the time and level of each nuclear development milestone a state reaches.
The lowest stage of nuclear development is classified as “nascent,” meaning the state does not yet have an operational nuclear reactor of any size. The proliferation curve begins in the year the state government makes the political decision to start a nuclear weapons program. Of the six proliferation curves shown in this chapter, only one state—China—began its weapons program at the lowest stage of nuclear development. Each of the other five states had existing nuclear infrastructure, at least at the reactor level, in place prior to the start decision.10
Stages 2 through 5 indicate progressive levels of enrichment and reprocessing capacity. The ability to produce fissile material to power nuclear weapons is a key hurdle to overcome in a nuclear weapons program. Whether a state decides to produce uranium or plutonium weapons—and in many cases both options are explored—this is the
most difficult step in producing nuclear bombs, as well as one of the most expensive.11 Most importantly, a state cannot produce nuclear weapons without highly enriched uranium or plutonium from a large reactor. For stages 2 and 3, I distinguish between small and large reactors using the power output threshold of 1 megawatt (MW).12 Reactors with design power greater than 1 MW have significant fuel requirements, and a large reactor is a necessary condition for the production of nuclear weapons.13 Several states, including India and Israel, produced the fissile material needed for nuclear weapons from large research reactors rather than from industrial-scale reactors.14 For stages 4 and 5, I distinguish between small and large uranium enrichment or plutonium reprocessing facilities. Large, industrial-scale facilities that use commercial technologies can produce significantly more weapons-grade uranium or plutonium than small, laboratory, or pilot facilities can.15
The last three stages indicate different levels of weaponization: a fission test, followed by deployable nuclear weapons, and finally a fusion (thermonuclear) test. These stages are separate from one another, as readers will note from the graphs; a state may test an atomic bomb but not build a nuclear arsenal, as India initially did, or a state may proceed directly to deployable nuclear weapons without first testing a device, as South Africa did. If a state reverses to the extent that the program regresses to an earlier stage of nuclear development, that is indicated on the graph.
Finally, dark, medium, and light gray shadings indicate the status of the program before and after each nuclear decision. Dark gray represents progress toward the bomb, while medium gray indicates that the program is continuing but is holding steady at its current level or is progressing very slowly due to reductions or a lack of interest from the government. Light gray indicates the program has been suspended, either permanently or temporarily.
I selected the six states represented here to provide a visual demonstration of proliferation curves that exhibit variation in several dimensions: the historical era of pursuit, whether the state ultimately acquired nuclear weapons, and regime type. I divide the nuclear
weapons age into three time periods: the “permissive” decades prior to the 1964 shock of the Chinese nuclear fission test, when major world powers—and a few minor powers—sought the bomb with few external constraints; the “transition period,” beginning with the 1965 start of the negotiations that would culminate in the Nuclear NonProliferation Treaty (NPT), during which a nuclear nonproliferation regime was emerging; and the “nonproliferation regime period,” characterized by the deepening of the nonproliferation regime, dating from the shock of the 1974 Indian peaceful nuclear explosion (PNE). Each of these periods constitutes a different global environment with different political and structural constraints on nuclear aspirants. I develop arguments for the significance of each historical period in Chapter 4.
I display two proliferation curves from each period in Figure 2.1. France and China were two of the original five countries to pursue nuclear weapons, beginning their programs within ten years of the end of World War II. India and South Korea were most active during the transition period between the early nuclear weapons states’ pursuits and the consolidation of the nuclear nonproliferation regime. India acquired nuclear weapons, while South Korea abandoned its program. Brazil and South Africa pursued nuclear weapons in the years after the Indian PNE, a shock that generated the political will to deepen the emerging nonproliferation regime. Brazil terminated its program, and South Africa acquired nuclear weapons and then later dismantled them.
