Tuesday, July 18, 2017

Technological Change and the Future of Nuclear Deterrence

Here's a change of pace for you, some strategic deterrence theory.

From Keir A. Lieber, and Daryl G. Press, at International Security, "The New Era of Counterforce: Technological Change and the Future of Nuclear Deterrence" (also in PDF):
Nuclear deterrence is based on the threat of retaliation. A nuclear arsenal designed for deterrence must, therefore, be able to survive an enemy first strike and still inflict unacceptable damage on the attacker. For most of the nuclear age, the survivability of retaliatory forces seemed straightforward; “counterforce” attacks—those aimed at disarming the enemy's nuclear forces—appeared impossible because the superpower arsenals were large and dispersed, and were considered easy to hide and protect. Today, analysts tend to worry more about the dangers of nuclear terrorism or accidents than the survivability of retaliatory arsenals. Nuclear deterrence appears robust.

Changes in technology, however, are eroding the foundation of nuclear deterrence. Rooted in the computer revolution, these advances are making nuclear forces around the world far more vulnerable than before. In fact, one of the principal strategies that countries employ to protect their arsenals from destruction, hardening, has already been largely negated by leaps in the accuracy of nuclear delivery systems. A second pillar of survivability, concealment, is being eroded by the revolution in remote sensing. The consequences of pinpoint accuracy and new sensing technologies are numerous, synergistic, and in some cases nonintuitive. Taken together, these developments are making the task of securing nuclear arsenals against attack much more challenging.

To be clear, nuclear arsenals around the world are not becoming equally vulnerable to attack. Countries that have considerable resources can buck these trends and keep their forces survivable, albeit with considerable cost and effort. Other countries, however—especially those facing wealthy, technologically advanced adversaries—will find it increasingly difficult to secure their arsenals, as guidance systems, sensors, data processing, communication, artificial intelligence, and a host of other products of the computer revolution continue to improve.

The growing vulnerability of nuclear forces sheds light on an enduring theoretical puzzle of the nuclear age. According to one of the leading theories of geopolitics in the nuclear era, the “theory of the nuclear revolution,” nuclear weapons are the ultimate instruments of deterrence, protecting those who possess them from invasion or other major attacks. Yet, if the theory is correct—that is, if nuclear weapons solve countries' most fundamental security problems—why do nuclear-armed countries continue to perceive serious threats from abroad and engage in intense security competition? Why have the great powers of the nuclear era behaved in many ways like their predecessors from previous centuries: by building alliances, engaging in arms races, competing for relative gains, and seeking to control strategic territory—none of which should matter much if nuclear weapons guarantee one's security? Although proponents of the theory of the nuclear revolution acknowledge this anomalous behavior, they attribute it to misguided leaders, bureaucratic pathologies, or dysfunctional domestic politics, not flaws in the theory itself.

Our analysis offers a simpler explanation for the disjuncture between the theory of the nuclear revolution's predictions and the foreign policy behavior of states: geopolitical rivalry remains logical in the nuclear age because stalemate is reversible. For nuclear weapons to revolutionize international politics—that is, to render countries fundamentally secure—the condition of stalemate must be enduring. Arsenals that are survivable today, however, can become vulnerable in the future. Nuclear-armed states thus have good reason to engage in intense competition, even if their own arsenals are currently secure. Stated differently, nuclear weapons are the best tools of deterrence ever created, but the possibility of acquiring disarming strike capabilities—and the fear that an opponent might do the same—explains why nuclear weapons have not transformed international politics.

The increasing vulnerability of nuclear forces also has several implications for nuclear policy. First, if nuclear forces are becoming easier to attack, then all else being equal, nuclear-armed states need to deploy more capable retaliatory arsenals to counter the growing risks. Whether one believes that a deterrent force must present potential attackers with “near-certain retaliation,” “likely retaliation,” or some other level of risk, improvements in counterforce systems require that retaliatory forces adapt—through better capabilities, increased numbers, or both—to maintain the same level of deterrent threat. Furthermore, the rapid rate of change in counterforce technologies increases uncertainty about adversaries' future capabilities, suggesting that countries will need to retain diverse retaliatory forces as a hedge against adversary breakthroughs.

Second, the increasing vulnerability of nuclear arsenals raises questions about the wisdom of future nuclear arms reductions. For decades, engineers have toiled to improve weapons accuracy and remote sensing capabilities. Meanwhile, arms negotiators have devised agreements to reduce nuclear arsenals, with the consequence of reducing the number of targets an attacker must destroy in a disarming strike. Either endeavor—improving weapons or cutting stockpiles—can be defended as a policy for promoting strategic stability, but taken together they are creating underrecognized vulnerabilities. The danger of nuclear arms cuts is exacerbated by improvements in nonnuclear means of attacking nuclear forces: for example, through precision conventional strike, missile defense, anti-submarine warfare (ASW), and cyber operations.

Third, the emergence of a new era of counterforce raises the question of whether it is wise, for the United States in particular, to continue improving nuclear and nonnuclear counterforce capabilities. On the one hand, improved counterforce capabilities could be invaluable in a range of plausible scenarios. Improved offensive capabilities could help the United States deter weak countries from initiating conventional conflicts or from escalating in the midst of war. Enhanced counterforce capabilities could also help protect U.S. forces, allies, and the U.S. homeland from nuclear attack if a conventional war did escalate. On the other hand, better counterforce could be a source of danger: not only might improved disarming strike capabilities—in any country's hands— increase the temptation to attack, but also potential victims of disarming strikes will seek to escape their vulnerability, thereby possibly triggering arms racing and incentives to strike preemptively.

Both views may be correct. The net benefit of decisions to enhance counterforce capabilities will therefore depend on the particular case. For countries that perceive a highly malign threat environment, face aggressive nuclear-armed adversaries, or have ambitious foreign policy goals, the benefits of developing advanced counterforce capabilities may outweigh the costs. For those countries that face a benign environment and have more modest goals, however, the secondary costs of enhancing counterforce may be too great. In any case, these contentious issues have not received sufficient attention; analysts and policymakers have largely overlooked the ways that rapidly changing technologies are eroding the foundation of deterrence.

The remainder of this article is organized as follows. We first discuss the key role that arsenal survivability plays in nuclear deterrence theory. Second, we describe the main strategies that planners employ to ensure arsenal survivability in practice. Next, we explore one of the major technological trends eroding survivability, the great leap in weapons accuracy, and illustrate how improved accuracy creates new possibilities for counterforce strikes. We then focus on the second major trend, dramatic improvements in remote sensing, and how the resulting increase in transparency threatens concealed and mobile nuclear forces. We conclude with a summary of our findings and their implications for international politics and U.S. national security.

Nuclear Survivability in Theory

At its core, nuclear deterrence theory rests on two simple propositions. First, countries will not attack their adversaries if they expect the costs to exceed the benefits. Second, nuclear weapons allow countries, even relatively weak ones, to inflict unprecedented levels of damage on those who attack them. Taken together, these propositions suggest that nuclear weapons are the ultimate instruments of deterrence: no conceivable benefit of attacking a nuclear-armed state could be worth the cost of getting hit with nuclear weapons in retaliation. As long as nuclear arsenals are survivable, that is, able to withstand an enemy's first strike and retaliate, nuclear weapons are a tremendous force for peace.

The theory of the nuclear revolution builds on the logic of deterrence theory and extends its implications. Because nuclear weapons make countries fundamentally secure, countries can escape the most pernicious consequences of anarchy. According to the theory of the nuclear revolution, once countries deploy survivable arsenals they no longer need to fear conquest. As a result, they can stop worrying about the relative balance of power; engaging in arms races; or competing for alliance partners and strategic territory.

Proponents of the theory of the nuclear revolution have always recognized the discrepancy between their theory's predictions and the actual behavior of countries in the nuclear era. The Cold War competition between the United States and the Soviet Union, in particular, is filled with empirical anomalies: extensive arms racing, intense concerns about relative power gains and losses, and competition for allies and control of strategic territory—all occurring at a time when the main adversaries appeared to be invulnerable to disarming strikes. World War III was averted, as nuclear deterrence theory would predict, but the transformation of international politics that advocates of the theory of the nuclear revolution anticipated never materialized. Today, nuclear powers still eye each other's economic power and military capabilities warily; strive for superiority over their adversaries in conventional and nuclear armaments; aim to control strategically relevant areas of land, air, sea, and space; seek to build and maintain alliances; and prepare for war.

The discrepancy between the theory of the nuclear revolution and the behavior of states stems from the theory's misplaced confidence in the survivability of nuclear arsenals.18 Proponents of the theory believe that nuclear weapons deployed in even moderate numbers are inherently survivable. Moreover, according to the argument, survivability is a one-way street: once a country deploys a survivable arsenal, it will remain that way. Yet, what if survivability is reversible?

If arsenal survivability depends on the uncertain course of technological change and the efforts of adversaries to develop new technologies, states will feel compelled to arms race to ensure that their deterrent forces remain survivable in the face of adversary advances. They will worry about relative gains, because a rich and powerful adversary will have more resources to invest in technology and military forces. They will value allies, which help contribute resources and valuable territory. Moreover, states may be enticed to develop their own counterforce capabilities in order to disarm their adversaries or limit the damage those adversaries can inflict in case of war. In short, if nuclear stalemate can be broken, one should expect countries to act as they always have when faced with military threats: by trying to exploit new technologies and strategies for destroying adversary capabilities. If arsenals have been more vulnerable than theorists assume, or if survivability and stalemate are reversible, then the central puzzle of the nuclear era—continued geopolitical competition—is no longer a puzzle.

We argue not only that stalemate is reversible in principal, but also that changes in technology occurring today are making all countries' arsenals less survivable than they were in the past. The fear of suffering devastating retaliation will still do much to deter counterforce attacks, but countries will increasingly worry that their adversaries are trying to escape stalemate, and they will feel pressure to do the same. Deterrence will weaken as arsenals become more vulnerable. In extreme circumstances—for example, if an adversary threatens escalation (or begins to escalate) during a conventional war—the temptation to launch a disarming strike may be powerful. In short, in stark contrast to the expectations of the theory of the nuclear revolution, security competition has not only endured, but also will intensify as enhanced counterforce capabilities proliferate...