Tripolar Nuclear Deterrence and U.S. Nuclear Strategy

• In Event: Nuclear Deterrence

Abstract

How does the emergence of China as a third major nuclear power affect U.S. nuclear strategy? China is engaging a in a buildup of its nuclear forces such that it is projected to equal the United States’ number of nuclear weapons by 2035. This will lead to a landscape in which the United States faces two nuclear peer adversaries at the same time. Scholars, policymakers, and military leaders recognize this “tripolar” or “multipolar” nuclear landscape is a new phenomenon distinct from the Cold War and the unipolar era that followed it. There is anxiety that the emergence of a tripolar nuclear world will render the lessons learned in previous nuclear eras obsolete. Indeed, scholars who are beginning to grapple with the problems of the new nuclear age argue that it represents unique challenges to controlling escalation and ensuring the integrity of command-and-control networks.

In my paper, I focus on the effect of a third major nuclear adversary on the missions and requirements of U.S. nuclear strategy. I argue that, by itself, the presence of a third major nuclear power should not change any of the missions given to U.S. nuclear weapons, and it only modestly increases the number of low-yield nuclear weapons required for fulfilling those missions. The emergence of a third major nuclear power would only lead to great changes in U.S. nuclear strategy if the United States wanted to have a theater nuclear warfighting capability or if new technologies made its second-strike capability uniquely vulnerable. A tripolar nuclear landscape is therefore what the major nuclear powers make of it, giving the United States latitude to pursue a wide range of nuclear postures and arms control measures.

I make this argument in five stages. First, I identify three missions that the United States has used its nuclear weapons to fulfill: 1) deterring a nuclear attack on the United States, 2) deterring nuclear attacks on allies, and 3) deterring conventional attacks on allies. Second, I argue that to fulfill these missions, the United States has settled on the maintenance of an assured destruction capability with the ability to use nuclear weapons first in a conflict along with some capacity to use low-yield nuclear weapons. These requirements are and have been contested, but this is where U.S. strategy settled towards the end of the Cold War and in the unipolar era. Third, I argue that the emergence of a third major nuclear power does not change the requirements for deterring a nuclear strike on the U.S. homeland or a nuclear strike against allies. The United States only needs to maintain a second-strike assured destruction capability against one of the major adversaries. An adversary is unlikely to launch a nuclear strike against the United States or one of its allies and court its own destruction just because another major power, even one that is an ally, will come out ahead.

Fourth, the emergence of a third major nuclear power could increase the doubt that the United States will run the risks of nuclear escalation to defend conventional attacks against its allies. This is because the United States may not want to engage in a crisis with one major adversary in the fear that it would embolden the other major nuclear adversary to start a conflict elsewhere. Such restraint could be overcome with a low-yield nuclear arsenal that can blur the line between conventional and nuclear conflict in multiple theaters. The emergence of a third major nuclear power therefore increases the requirements of deterring conventional attacks against allies, but it does so by only modestly increasing the burden on the United States’ low-yield nuclear arsenal.

Fifth, the changes to U.S. nuclear strategy caused by the growth in China’s nuclear arsenal could be larger, but only if U.S. policymakers make certain assessments of their security challenges. For example, if the United States wanted to maintain a limited nuclear warfighting capability, then facing two major nuclear adversaries would pose a much larger challenge to the nuclear enterprise. If U.S. policymakers thought that China and Russia were fielding new technologies that made its strategic nuclear arsenal uniquely vulnerable to a disarming first strike, then the United States would need to increase the number of strategic nuclear weapons beyond the limits specified in the New START treaty.

The former possibility is a choice that policymakers can make, and the latter possibility can be mitigated by pursuing arms control agreements with China and Russia. The implication for policymakers is that the emergence of a third major nuclear power does not, by itself, cause lessons from previous nuclear eras to become obsolete or force any big changes in U.S. nuclear strategy. The tripolar nuclear age is what the major nuclear powers make of it. The United States therefore can and should consider a range of nuclear postures and arms control measures in the tripolar nuclear age.

Author

• Tyler Bowen, United States Naval War College