A new report from the Brookings Institution presents evidence that increasing the size of the U.S. nuclear arsenal could make nuclear crises more likely. This raises an important challenge to arguments that the U.S. must think about increasing its stockpile in response to China's growing nuclear capabilities.
For decades, the U.S. nuclear stockpile has held steady at around 5,000 warheads. Until recently, most experts agreed that this supply was adequate to persuade adversaries that any nuclear attack would lead to devastating consequences, a calculation that experts agree serves as an effective deterrent. With nuclear adversaries, this is the condition of credible mutually assured destruction, in which the ability to strike first does not eliminate the other side's ability to strike back. In recent years, however, some experts have begun to worry that the U.S. arsenal cannot credibly deter China and Russia at the same time.
Because there is no way to directly test this claim, the report, by Brookings senior fellow Melanie W. Sisson, uses evidence from historical instances in which the United States made, or received, nuclear threats. It found that events—such as the Cuban Missile Crisis, confrontations with North Korea, and Russia's threats to deploy nuclear weapons in Ukraine—were more common when one side had a substantial advantage over the other (usually the United States).
Crises were less frequent when the U.S. and its nuclear adversary approached rough parity in nuclear capability. Other factors, including where and how many warheads were deployed, and the specific doctrines governing U.S. nuclear policy, showed no consistent association with crisis frequency.
As of now, the U.S. has far more nuclear warheads than China. According to the Bulletin of the Atomic Scientists, the U.S. has around 5,000 warheads, while Russia has a little less than 5,500. China currently has around 600. In recent years China has been working to increase its nuclear arsenal, but the report notes that the current U.S. arsenal will remain able to retaliate if attacked, even if China and Russia were to team up against the U.S.
The report's findings have crucial implications for the future of U.S. defense strategy. Sisson argues that rather than spending billions to expand its nuclear arsenal, the U.S. should instead focus its efforts on enhancing its survivability and resilience. For instance, she says, the U.S. should continue to strengthen the capabilities of its nuclear submarine fleet. It should also focus more on defending U.S. nuclear command and control systems against possible AI-enabled cyberattacks, which could degrade or disable U.S. capability to use its nuclear arsenal in response to an attack.
