Conventional Deterrence in the Second Nuclear Age

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Deterrence is once again a topic of discussion and debate among US defense and policy communities. Although the concept has received comparatively little attention since the end of the Cold War, it seems poised to take center stage in America's national security policy during the coming decades. Adversary-specific deterrence strategies will likely become prominent in national and international security decisions for an increasingly multipolar world, with two wars already straining the military, concerns about a recalcitrant and militarized Russia, Iran's continued uranium enrichment activities, North Korea's nascent nuclear arsenal, and top-to-bottom military modernization in China.

As part of this renewed interest in deterrence, conventional weapons are playing an important role. The "New Triad," consisting of both nuclear and advanced conventional weapons; proposals for conventionally armed intercontinental ballistic missiles; and, more generally, the concept of Prompt Global Strike all represent a growing belief that advanced conventional capabilities can substitute for some missions previously relegated solely to nuclear weapons. Although there has been considerable debate over these specific initiatives--for example, the effect that putting conventional warheads on ballistic missiles would have on strategic stability-most specialists agree that conventional forces can help reduce the role of nuclear weapons in US security strategy. In fact, in recent years the US military has expanded the concept of "strategic deterrence," a term that once encompassed only intercontinental nuclear weapons, to incorporate both nuclear and conventional forces, as well as diplomatic, economic, and informational tools. (1)

The recent emphasis on substituting conventional for nuclear weapons in selected missions is an important step in developing a credible and robust twenty-first century deterrent, but it does not fully consider the unique logic and strategy of conventional deterrence. The current debate focuses primarily on the use of conventional weapons for "deterrence by punishment," the threat to impose unacceptable costs, such as the destruction of an adversary's strategic and high-value targets, in response to unwanted actions. Yet, one of the most important contributions of conventional forces is "deterrence by denial," the threat to deny an adversary the ability to achieve its military and political objectives through aggression. (2) If early strategists were accused of "conventionalization" by treating nuclear weapons merely as more powerful and effective tools of war, the current debate regarding conventional contributions to deterrence may be accused of "nuclearization," in that it treats conventional capabilities merely as a substitute for nuclear weapons.

The following assessment has the purpose of expanding the discussion related to the role and utility of conventional forces in US strategies by reexamining the traditional logic of conventional deterrence. That logic focuses primarily on deterrence by denial, in the context of the modern international security environment. It is primarily concerned with the role of US conventional forces in extended deterrence, defined as the threat of force to protect allies and friends, rather than "central" or "homeland" deterrence. (3) This focus on extended deterrence, and especially on the role of deterrence by denial, highlights the importance of protecting territory from attack and invasion. Historically, the desire for control over specific territory has been a frequent motivator of interstate crises and conflict. (4) While interstate conventional wars have significantly declined since the end of the Second World War, the potential for conflict over Taiwan or on the Korean Peninsula, the prospect of future clashes over control of scarce natural resources, and the 2008 war between Georgia and Russia attest to the continued possibility of conflict over specific territory that has important strategic, economic, political, religious, historical, or socio-cultural significance.

Consequently, this article examines how US conventional military power can be used to deter conventional aggression against friends and allies by threatening to deny an adversary its best chance of success on the battlefield--a surprise or short-notice attack with little or no engagement with American military forces. The ability to prevent an opponent from presenting the United States with a fait accompli--that is, from striking quickly and achieving victory before substantial US (and perhaps coalition) forces can be deployed to the theater--is a central component of modern conventional deterrence.

Conventional Deterrence in US Strategy

Broadly defined, deterrence is the threat of force intended to convince a potential aggressor not to undertake a particular action because the costs will be unacceptable or the probability of success extremely low. This threat has always been one of the central strategic principles by which nations attempted to prevent conflict. (5) Even so, the development and rigorous analysis of deterrence as a discrete strategic concept did not occur until the advent of nuclear weapons.

Deterrence theory was developed against the backdrop of the Cold War nuclear arms race and focused on the prevention of nuclear conflict. Yet, while the majority of academic research and public debate was concerned with the prevention of nuclear war--the net result was that deterrence became synonymous with nuclear weapons--conventional deterrence, appropriately, assumed an increasingly important role in the development of military strategy during this period. (6) As the Soviet Union began to amass a large and survivable nuclear arsenal that was capable of global reach in the late 1950s and early 1960s, the credibility of the Eisenhower Administration's policy of "Massive Retaliation," which threatened an overwhelming nuclear response to virtually any Soviet aggression, was brought into question. Once the Soviet Union developed capabilities that could reach the US homeland, many defense officials and analysts argued that the threat of Massive Retaliation lacked usefulness against anything other than an all-out Soviet nuclear attack. (7)

As a result, western military strategy eventually shifted from total reliance on nuclear weapons as a means of deterring both Soviet conventional and nuclear aggression to a strategy of "Flexible Response," which included conventional and nuclear elements. From the mid-1960s onward, NATO relied on conventional power, backed by the threat of nuclear escalation, to deter any conventional assault on Europe by the numerically superior Warsaw Pact, and relied on nuclear weapons to deter nuclear attacks. (8) By incorporating "direct defense"--the ability to respond to Warsaw Pact aggression, especially conventional aggression, with proportionate (i.e., conventional) force--into NATO strategy, the concept of Flexible Response sought to create a more credible means of deterrence across the entire spectrum of conflict.

Following the Cold War, conventional deterrence earned an even greater role in US national security strategy. With the demise of the Soviet Union and significant advancements in conventional precision-guided munitions, many defense analysts concluded that "smart" weapons could provide a powerful deterrent against a wide variety of threats. While some commentators argued that nuclear weapons were still necessary to prevent nuclear attacks, and others contended that conventional weapons were "the only credible deterrent" even against nuclear threats, almost all agreed that technologically advanced conventional weapons could now take the place of nuclear weapons in many missions. (9) Following the remarkable success of sophisticated conventional firepower in Operation Desert Storm, William Perry declared, "This new conventional military capability adds a powerful dimension to the ability of the United States to deter war." (10)

In the current international security …