The Decline of Deterrence

The Bottom Line

• Deterrence is not as stable as believed, and is becoming less so.
• Deterrence strategies are under assault on a number of fronts—geopolitical, military-technical, and geostrategic—and are even being challenged by advances in the cognitive and social sciences.
• Time is not on our side. The new administration must move quickly to stem the erosion of deterrence strategies and restore their efficacy.

Introduction

Following the enormous human and material losses in two world wars, which ended with the use of nuclear weapons, it became clear that the next general war would produce no winners, only survivors. Thus deterrence became the foundation of U.S. defense strategy for avoiding general wars, both nuclear and conventional. Deterrence involves efforts to prevent a rival, or “target,” from pursuing a proscribed action. This is done by influencing the target’s calculation of the costs, benefits, and risks associated with engaging in the proscribed action. Deterrence works by convincing the target that it has an unacceptably low probability of achieving its goals (deterrence through denial), or that the costs incurred through pursuing the proscribed action will exceed any benefits derived (deterrence through punishment).

Although deterrence held during the Cold War, on several occasions the United States and Soviet Russia came perilously close to nuclear Armageddon. Russia’s military decline following communism’s collapse found America enjoying a period of military dominance that appeared to guarantee none of its rivals would risk a general war. With the return of intense geopolitical competition between the United States and the revisionist great powers, China and Russia, this happy state of affairs no longer obtains, if it ever did.

During the past decade, as the era of U.S. military dominance has faded, both the Obama and Trump administrations have addressed deterrence—a centerpiece of both national defense strategies—in only the most general terms. The unstated assumption has been that what worked during the Cold War and the two decades of U.S. military primacy that followed will ensure deterrence remains robust in the future. Yet the conditions under which military dissuasion must function are changing—and in nearly every case they are eroding its efficacy.

With this in mind, the drafters of the next National Defense Strategy should undertake a fundamental assessment of how deterrence strategies must be adapted in order to succeed under new and very different geopolitical and military-technical circumstances that include growing military competition in relatively new warfare domains and advances in the cognitive sciences.

Geopolitical Transition

Today the United States confronts two revisionist great powers in China and Russia. Unlike the Cold War bipolar international system or the U.S.-dominated unipolar world that succeeded it, today’s world is increasingly multipolar, both politically and militarily. If nothing else, this increase in the number of rivals the United States seeks to deter provides more opportunities for deterrence to fail.

The shift toward a multipolar world is particularly pronounced with regard to nuclear weapons. Following the Cold War, America and Russia dramatically reduced their nuclear arsenals, lowering the “entry barrier” to states aspiring to become major players in the “Nuclear Club.” Thus far none have reached that status, but China, as well as new members India, North Korea, and Pakistan are all expanding and improving their arsenals.¹ This portends problems for deterrence. For example, both the United States and Russia have long considered parity—a rough equivalence in nuclear capability—an essential feature in their arms control agreements to enhance deterrence by ensuring both sides could maintain the ability to inflict massive “assured destruction” after suffering a surprise first strike. Parity was possible in what was effectively a bipolar nuclear competition during the Cold War. It is not possible, however, for every power in a multipolar nuclear competition to enjoy parity with its rivals.

The increasingly dynamic geopolitical environment further complicates matters. The disposition of nuclear powers such as Pakistan, which risks falling into China’s orbit, is unclear. North Korea is seeking to create a nuclear arsenal whose size would have given Truman and Eisenhower pause. The potential for rapid shifts in geopolitical alignments, and the nuclear balance, could pose significant challenges for U.S. deterrence strategy.

Military-Technical Advances

The development of near-zero-miss conventional weapons suggests that, at least in some cases, these precision-guided munitions may be capable of substituting for nuclear weapons against certain kinds of targets. This further complicates efforts to assess the strategic military balance. Moreover, states such as Russia that cannot match the U.S. precision warfare capability are fielding nuclear weapons with very low yields to offset the American advantage.² Both Chinese and Russian military writings talk of employing nuclear-generated electromagnetic pulse attacks.³ These developments are eroding the clear “firebreak” that once existed between the use of conventional and nuclear weapons. Deterrence may be compromised if U.S. leaders discount the risk that a conventional war involving widespread use of precision-guided weapons against strategic targets could escalate to nuclear war. Meanwhile, their Chinese and Russian counterparts believe their “discriminate” nuclear weapons will not trigger escalation to general nuclear use.

Cyberweapons may pose a serious threat to a state’s early warning and command and control systems. The same is true for nuclear powers armed with ballistic missiles in close geographic proximity to one another, as is the case with India and Pakistan, for example, or, prospectively, with Iran and Israel.

Fears that cyber malware may compromise early warning or corrupt command and control systems could find political leaders losing confidence in their ability to receive warning of an attack or effectively communicate their orders to retaliate. The same fears could obtain if ballistic missiles from close neighbors so compress warning time that even instantaneous attack detection would not provide enough time to prepare an effective response. If so, leaders may delegate nuclear (or strategic) force release authority to lower-level commanders, which would put more fingers on the nuclear trigger and thereby increase the risk of accidental or unauthorized use.

Devolving strategic force release authority could also increase a prospective attacker’s incentive to strike, lest one of its rival’s independent commanders should decide to strike first. This incentive may increase if a potential aggressor were to believe its opponent’s warning and response systems could be compromised, since that would lower the risk of undertaking an attack. Simply put, the development of cyber weapons as well as weapons offering high speed of attack and geographic proximity pose significant challenges for strategies relying on deterrence.

The true (as opposed to “advertised”) effectiveness of relatively new but untested military capabilities and those that may emerge over the next decade—such as hypersonic missiles, robotic swarms and CubeSat architectures—remains relatively ambiguous, due to the (thankfully) long absence of general war between major military powers. This uncertainty may find prospective belligerents reaching significantly different conclusions on the military balance. To the extent they reach optimistic conclusions regarding these capabilities’ contributions to their side of the balance, it could lower the perceived costs and risks of war.

New Warfighting Domains

Recent decades find military competition expanding in the relatively new domains of space, cyberspace, and the seabed. In each one, the competition favors the offense: All other factors being equal, the costs associated with taking a proscribed action are less than those needed to mount a successful defense, and this undermines deterrence through denial.

Moreover, in each domain, identifying the source of an attack—especially promptly—is relatively difficult by comparison with large-scale attacks in more traditional warfighting domains, such as land, air, and sea. This may lower the perceived risk associated with pursuing a proscribed action in these domains and, in so doing, incentivize risk-tolerant actors—which erodes the efficacy of deterrence through punishment.

Advances in the Cognitive Sciences

Understanding how a rival engages in risk management is central to developing effective deterrence strategies. The underlying assumption is that the rival decisionmaker will act rationally, in line with his risk profile.

Unfortunately, advances in the cognitive and behavioral sciences reveal that humans cannot be counted on to act rationally in making decisions where risk is involved. The emergence of prospect theory, for example, finds people are relatively reluctant to run risks to acquire what they do not have, and more willing to do so when it involves preserving that which they believe is theirs.⁴ This would seem to fortify deterrence. Problems arise, however, when both rivals view themselves as being in a “domain of loss,” and are thus willing to run relatively high risks in order to prevail. This dynamic is at work in the South China Sea, where Beijing increasingly sees its creeping territorial expansion being progressively less a claim and increasingly an established fact, while other powers continue viewing it as illegitimate. In a crisis, both parties may see themselves in a domain of loss. If so, both would be willing to run unusually high risks to achieve their aims.

Another advance in the cognitive sciences concerns optimism bias,⁵ or the tendency of successful individuals—like political leaders—to discount risk. This is particularly worrisome with respect to tyrants, who often must run great risks on the way to seizing power. Their experience in beating the odds can enhance the danger that they will discount risk. If so, deterring them becomes more difficult.

Nebulous concepts such as fairness and honor can skew a decisionmaker’s rational calculations. Research in the social sciences finds that participants across a range of cultures have very different ways of calculating cost, benefit, and risk, and are also prone to reject win-win outcomes in favor of lose-lose outcomes if they feel they are being treated unfairly or with a lack of respect.⁶ Understanding the affect these factors have on rival leaders' decisionmaking will be important if deterrence strategies are to avoid lose-lose outcomes.

Recommendations

Irrespective of which political party gains the White House, the United States shows every indication of continuing its reliance on deterrence as a centerpiece of its defense strategy. If so, the trends outlined here warrant the kind of sustained intellectual effort by the nation’s best strategists to adapt deterrence strategy to today’s realities. Toward this end, the Defense Department might usefully pursue the following recommendations:

• Understand the Competition: Deterrence lies in the eye of the beholder. During the Cold War, the Department devoted persistent, intense effort to understanding how Soviet leaders calculated cost, benefit, and risk, as well as how they viewed the strategic military balance and the balance in key regions. A similar effort needs to be undertaken today, with priority given to China, followed by Russia. Net assessments of these balances can aid policymakers in identifying areas of weakness and prospective opportunities to enhance the U.S. defense posture’s deterrent effect.
• Rethink Escalation Dynamics: The very different environment in which contemporary deterrence strategies must function suggests a need to update the vertical and horizontal escalation “ladders,” which were generally ignored following the Cold War. As the term suggests, the ladder rungs mark quantum leaps in conflict intensity (vertical escalation) or geographic spread (horizontal escalation), and they identify important points for deterring rivals from escalating. After these ladders are updated, work can begin on fortifying those rungs that need to be strengthened to enhance deterrence. Because deterrence lies in the eye of the beholder, understanding how America’s rivals view escalation will be essential to success.
• Close the Attribution Gap: Failure to identify the source of an attack, and to do so promptly, risks undermining deterrence strategies based on the threat of inflicting prompt, unacceptable punishment on the aggressor. The problem might be ameliorated through increased intelligence efforts, particularly human and signals intelligence.
• Keep Options Open: There is a saying that the budget, not strategy, drives the Defense Department. Defaulting to “program momentum” would be especially risky in an era in which the character of warfare is changing rapidly, and where defense budgets are likely to come under ever-greater pressure as the consequences of a generation of poor fiscal stewardship and the costs of Coronavirus disease-19 come home to roost. Given that the means and methods of deterrence are likely to require significant adjustments, priority should be accorded to maximizing the Department’s investment options until a new defense strategy and the requirements for deterrence can be identified.

Conclusion

As long as deterring wars remains central to preserving the nation’s security, crafting and executing effective deterrence strategies will remain central to the Department’s work. Myriad trends indicate that strategies founded on deterrence are becoming more difficult to construct and implement. Yet the price to be paid, should deterrence fail and general war ensue, make it imperative that the next administration dedicate itself to ensuring that this cornerstone of U.S. defense strategy rests on a solid foundation.

About the Author

Andrew F. Krepinevich Jr. is an Adjunct Senior Fellow at CNAS.

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