How many nuclear weapons is enough? The question has haunted policymakers and scholars for 80 years. Early in the Cold War, the United States expanded its nuclear arsenal rapidly in response to the Soviet threat. But beginning in the 1980s, as the two nuclear powers sought ways to reduce nuclear risks, arms treaties helped cut the size of those arsenals significantly, and stockpiles decreased by 80 percent. Now, circumstances are pushing the United States to consider the size of its nuclear arsenal once again. Over the past six years, China has nearly tripled the number of nuclear weapons it has, and according to the U.S. Defense Department, the country is on track to have over 1,000 by 2030. China is not yet a nuclear peer to Russia and the United States, which each deploy roughly 1,550 nuclear weapons in keeping with the limit set by the 2010 New Strategic Arms Reduction Treaty, but parity may be Beijing’s goal. Meanwhile, the last formal barrier to a U.S.-Russian arms race fell away when New START expired earlier this year.

Faced with these rising dangers, the Trump administration announced in March that it would conduct what it called a “nuclear strategy review.” Some strategists recommend that the review include a call for a larger and more diverse nuclear arsenal. A larger arsenal, proponents of expansion argue, would provide the United States with a wider array of choices, especially for an in-kind response to low-yield theater nuclear attacks. Although Russia and the United States have nearly the same number of weapons, Russia possesses a greater number of theater nuclear weapons, which, unlike strategic nuclear forces, are designed for tactical use on the battlefield. China may also be developing more of these types of weapons. Advocates of expansion propose that if Washington can match any nuclear attack blow for blow, Beijing and Moscow will be less likely to initiate a nuclear exchange. According to Trump administration officials, the nuclear review will look at this “theater nuclear forces issue” to “identify where there may need to be changes or additions made.”

The United States should take additions to its nuclear forces off the table. The country already has a vast and diverse enough supply of nuclear weapons to unleash devastation on an adversary in the case of a nuclear attack. The purpose of nuclear deterrence is not to have an answer for every weapon in an adversary’s arsenal, but to avoid crossing the nuclear threshold in the first place. Moreover, introducing new theater weapons could provoke an arms race for which the United States is ill equipped and invite risks of inadvertent escalation that would only make the country more vulnerable. Rather than focus on expanding and diversifying the U.S. nuclear arsenal, Washington’s deterrence strategy should attend to the modernization of its existing strategic forces, which is behind schedule, and of its conventional arms, which are not fit to deter the United States’ greatest military threats, especially Chinese military aggression in the Western Pacific.

When the foundations of U.S.........

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