The Case for Overkill

On Wednesday, President Obama gave a speech at the Brandenburg Gate in Berlin, calling for the United States and Russia to reduce the size of their deployed nuclear arsenals by one-third to around 1,000 strategic warheads. The call for further cuts has been greeted with enthusiasm in many quarters, but these proposed nuclear reductions could potentially be highly damaging to U.S. interests.

In his speech, the president argued that such cuts would be consistent with the goal of maintaining "a strong and credible strategic deterrent," but this argument rests on a contested theory about how nuclear deterrence works. The Obama administration, and many scholars and experts, believe that a secure, second-strike capability is sufficient for deterrence and that anything more is "overkill." Therefore, they believe that nuclear warheads in excess of a "minimum deterrent" threshold can be cut with very little loss to our national security.

However, there are those who argue that maintaining a nuclear advantage over one’s opponents enhances deterrence. As Paul Nitze argued during the Cold War, it is of "the utmost importance that the West maintain a sufficient margin of superior capability…. The greater the margin (and the more clearly the Communists understand that we have a margin), the less likely it is that nuclear war will ever occur."

For decades, this debate was largely theoretical — neither camp marshaled systematic evidence in support of its views — but, recently, I methodically reviewed the relationship between the size of a country’s nuclear arsenal and its ability to achieve its national security objectives. I found strong evidence that, when it comes to nuclear deterrence, more is better.

In an analysis of 52 countries that participated in nuclear crises from 1945 to 2001 (think the Cuban Missile Crisis), I found that the state with the greater number of warheads is over 17 times more likely to achieve its goals. In addition, there is qualitative evidence from these crises that leaders in nuclear-armed states pay close attention to the nuclear balance of power, that they believe nuclear superiority enhances their position, and that a nuclear advantage often translates directly into a geopolitical advantage. For example, during the Cuban Missile Crisis, Secretary of State Dean Rusk argued, "One thing Mr. Khrushchev may have in mind is that… he knows that we have a substantial nuclear superiority…. He also knows that we don’t really live under fear of his nuclear weapons to the extent… that he has to live under ours."

Even if Russia agrees to match the president’s proposed cuts, the nuclear reductions would attenuate our advantages vis-à-vis Russia and eat into our margin of superiority against other nuclear-armed states, such as China, possibly increasing the likelihood that the United States will be challenged militarily and reducing the probability that we achieve our goals in future crises.

If there is at least some reason to believe that reductions could harm America’s strategic deterrent, then certainly those in favor of reductions provide concrete evidence that the benefits of reductions outweigh these costs, right? Alas, they do not.

Supporters of further cuts argue that reducing the role of nuclear weapons in U.S. policy will help us stop the spread of nuclear weapons to other countries. They argue that our large nuclear arsenal makes it difficult (if not hypocritical) to tell, say, Iran that it cannot have nuclear weapons, or to demand that other non-nuclear countries (such as Brazil and Turkey) help us pressure Iran. Therefore, they argue, we can generate goodwill and strengthen our nonproliferation efforts by cutting our own nuclear arsenal.

This argument makes sense at a superficial level, but on closer inspection it falls apart. As Iran’s leaders decide whether to push forward with, or put limits on, their nuclear program, or as Brazilian and Turkish leaders think about getting tougher with Iran, they likely consider many things, but it is implausible that the precise size of the U.S. nuclear arsenal is among them. The evidence backs this logic up; the United States has been cutting the size of its nuclear arsenal since 1967, but there is no reason to believe that we have ever received any credit for doing so, or that these cuts have contributed to any breakthroughs on important nonproliferation problems. In short, we can’t stop other countries from building nuclear weapons by getting rid of our own.

Finally, proponents of cuts claim that nuclear reductions will lead to cost savings in a time of budget austerity, but, at least in the short term, nuclear reductions will actually result in cost increases, not decreases. Cutting arsenal size means pulling missiles out of silos, erecting buildings in which to store them, dismantling retired warheads, and decommissioning nuclear facilities. All of this costs money. Only if we think we can maintain a diminished nuclear posture indefinitely is it plausible to think there might be marginal cost savings to be had over the long run. But this would be an unwise bet given that U.S. competitors, including China, are moving in the opposite direction, expanding and modernizing their nuclear forces.

Since there are potential strategic costs and no identifiable benefits to further reducing the size of the U.S. nuclear arsenal, the United States should refrain from making any additional nuclear reductions. It must not go below the 1,550 warheads agreed to in New START (and it should take its sweet time getting down to that number). In addition, the United States should maintain the "hedge" of weapons it keeps in reserve at current levels and halt the transfer of warheads from storage to retirement and elimination. Finally, the Obama administration must follow through on its promise to fully invest in modernizing U.S. nuclear infrastructure so that it does not lose the capability to sustain a safe, secure, and effective nuclear arsenal for decades to come.

Some may find this argument provocative, but it is actually quite anodyne; I recommend simply that the United States maintain the status quo. What is provocative is slashing America’s nuclear arsenal to 60-year lows in the face of evidence suggesting that doing so will harm our national interests.