Table of Contents

The number of countries that pose threats requiring the United States to maintain nuclear weapons is few, as are the threat scenarios that would make it necessary and prudent for a U.S. president to order the use of these weapons. This good news is the result of many factors, not least of which is the essential caution that nuclear weapons inspire in those who possess them and those who may be targeted by them. Yet the present need for nuclear deterrence in general does not take policymakers and citizens very far in determining “how much is enough” to deter given adversaries, or in determining “how much is too much.” Policymakers often err on the side of caution, but what is cautious depends on context and how risks are defined. During the Cold War, an overly cautious approach to “how much is enough” led the United States and the Soviet Union to accumulate nuclear arsenals with enough destructive power to wipe out much of humanity.

For those whose primary job is to deter major warfare, especially nuclear war, and to prevail if deterrence fails, caution means ensuring that one’s own military has a sufficient variety and numbers of conventional and nuclear weapons systems and plans to use them to counter those held by one’s strongest adversary. This perspective operates in the defense establishments of most nuclear-armed states, including the United States. While nuclear parity is not necessary to deter Russia, no U.S. political candidate or party wants to compete for elections by arguing it is sufficient for the United States to have fewer nuclear weapons than Russia or anyone else. This is why “second to none” is the politically safe policy to espouse. But if risk and national security requirements are assessed in a wider, more holistic context, the question “how much is enough?” must be balanced by also asking “how much is too much?” Are there conventional force postures, or specific types and numbers of nuclear weapons and targeting policies, that make the risk of starting or escalating nuclear war unnecessarily high, and make the prospect of global catastrophe too likely? Are the probability and consequence of deterrence failure with U.S. and Russian arsenals worse than the risk of failure with less destructive arsenals more like those of the seven other nuclear-armed states?

The number of countries that pose threats requiring the United States to maintain nuclear weapons is few, as are the threat scenarios that would make it necessary and prudent for a U.S. president to order the use of these weapons.

There are no certain answers to these questions—not in the United States, Russia, China, or anywhere else. The challenges and dilemmas inherent in answering these questions are too broad and portentous to leave them to defense establishments to resolve. Other policymakers, as well as informed citizens, need to be more engaged in these issues. The analyses and recommendations offered in these pages are debatable. Indeed, our objective is to encourage open, informed national and international debate on U.S. nuclear policy and that of its competitor countries in this domain.

Acknowledgments

The authors deeply appreciate the generous support of the MacArthur Foundation, the Edgerton Foundation, and the Carnegie Corporation of New York for this project.

We have gratefully benefited from the external counsel of more than twenty officials and experts from nine countries and NATO representing a range of views regarding nuclear weapons policy. Their critiques of our initial draft were invaluable even if responsibility for this product is ours alone.

The authors owe a special thanks to Nicholas Blanchette, Megan DuBois, Garrett Hinck, and Gaurav Kalwani, whose contributions as research staff for this project were indispensable.