A recent op-ed in the New York Times urged President Obama to reverse decades of official U.S. nuclear doctrine and openly commit the United States to a no-first-use policy. Polls suggest that the American public would likely support an end to the first-use doctrine, but David Sanger and William Broad recently reported that Obama is unlikely to adopt such a change. In the wake of the outrage surrounding North Korea’s latest nuclear test, why would it be beneficial for the United States to retain the option of first use?

In this article I consider two situations in which the United States might introduce nuclear weapons. With these optimistic scenarios in mind we can then evaluate the drawbacks of maintaining a first-use doctrine and consider whether the doctrine itself provides any benefits for U.S. national strategy. Although we may dislike the idea of the United States launching a first strike, retaining the option to do so may be the best way for the United States to achieve its strategic objectives given current constraints on its ability to deploy additional conventional forces.

First-Use Scenarios

Imagine that the United States detected an imminent conventional attack on South Korea. The United States might decide to launch a first strike on North Korea’s nuclear facilities to prevent it from using its nuclear weapons against South Korea. (A “first strike” usually refers to a nuclear strike like this one, in which one state launches a nuclear attack designed to eliminate the opponent’s nuclear arsenal. “First use” describes the use of nuclear weapons before the opponent has done so and could entail the use of smaller tactical nuclear weapons on the battlefield. In these terms, all first strikes constitute a first use of nuclear weapons, but not all cases of first use would be considered a first strike.) This would protect both South Korea and American troops on the peninsula from a nuclear attack. North Korea does not yet have a missile capable of delivering a nuclear weapon to the continental United States, so the immediate risk to the American homeland would be minimal in the event that the first strike failed to eliminate all of North Korea’s nuclear weapons.

On the other hand, consider the case of an impending Russian attack on Estonia. The United States does not currently have sufficient forces deployed in the Baltics to effectively repel an invasion, nor will the battalion planned for deployment in Poland be an effective deterrent to a Russian attack. American forces in Estonia would be at a huge disadvantage over their Russian counterparts fighting so close to their homeland with short lines of communication. A tactical nuclear weapon strike on Russian troops before they crossed the border into Estonia might allow the United States to destroy Russian forces and deter an additional attack without exposing American troops to a grinding ground war with Russia.

The Baltic scenario is in many ways more troubling than the Korean peninsula. Russia is capable of launching a retaliatory nuclear attack on the continental United States, and using nuclear weapons on the Russian border of Estonia could possibly destroy the very territory that the United States is trying to protect from invasion. This could be true in the Korean scenario as well. Seoul is far enough from the demilitarized zone (DMZ) that that it could remain relatively unharmed by a small detonation in North Korea, but this is a risk in both scenarios.

The Possibility of First Use: Deterrence by Ambiguity

Keeping these two scenarios in mind, we can also distinguish between what the United States would actually do in a crisis and what it is useful for the United States to have others believe it might do in a crisis. If North Korea believes that the United States could use nuclear weapons to prevent or repel an invasion of South Korea, then it may be less willing to launch that invasion in the first place. Some might argue that the fear that the United States could launch an attack to eliminate the North’s nuclear weapons would give Kim Jong-Un an incentive to launch his own weapons preemptively lest he lose the ability to use them. This would make sense only if we believe that the North Korean leader wants to invite his own demise as part of his plan to take South Korea, since any use of a nuclear weapon by North Korea would result in swift retaliatory nuclear annihilation.

The logic also applies in the case of a Russian invasion of the Baltics. The battalion in Poland will not persuade Russia that the United States is heavily invested in Estonia’s independence, but perhaps the possibility—however remote—of an American nuclear attack on Russian troops might be enough to persuade Putin not to invade. If the United States openly disavowed the option of first use, it would lose this possibility of deterring an attack through ambiguity.

The argument that the possibility of first use can be an effective deterrent of a North Korean or Russian invasion assumes that the opponent believes (at least to some extent) that the United States would actually carry out such an attack. This raises a central dilemma concerning the role of nuclear weapons in American foreign policy: Does anyone believe that the United States would use them? In other words, is the threat to use nuclear weapons sufficiently credible that it would actually influence the behavior of other states or do opponents discount the possibility of use so heavily that the United States’ nuclear weapons have no impact on these opponents’ calculations? Some recent research suggests that non-nuclear states do not assume that nuclear-capable opponents would refrain from using their nuclear weapons in a crisis. In the two scenarios we are considering, however, the United States would be facing states that also have nuclear weapons, so we cannot be sure these findings apply.

Russia’s official nuclear doctrine may provide some insight. The Soviet Union maintained a no-first-use policy until Russia renounced it in 1993. In response to NATO’s impressive 1999 air campaign over Kosovo, Russia realized that it could not match the United States’ capability in conventional precision munitions and explicitly incorporated the first use of nuclear weapons into official doctrine. It also introduced the concept of a small nuclear strike for the purpose of “de-escalation” if it faced a conventional attack to which it could not respond in kind. The theory was that the limited use of nuclear weapons would force Russia’s opponent to de-escalate the conflict. Russia scaled this back somewhat in 2010 with a new nuclear doctrine that permits the use of nuclear weapons only when “the very existence of the state is under threat.”  In other words, Russia considers the first use of nuclear weapons to be a possible option for achieving its national security objectives, so it is likely that it takes seriously the United States’ doctrine for doing so, as well.

Benefits Beyond Deterrence?

Adopting a no-first-use doctrine would allow the United States to remove the tactical nuclear weapons that are currently deployed in Europe. This seems to provide an opportunity for cost-saving, but in fact reliance on first use was motivated in part by the desire to minimize U.S. costs for defending Western Europe. President Eisenhower did not want to station huge numbers of American troops in Europe on a permanent basis, so relying on the U.S. nuclear arsenal seemed to be a cheaper way to defend NATO. If the United States has decided that defending the Baltics from a Russian attack and South Korea from its northern neighbor are core strategic interests, then taking nuclear weapons off the table would probably prompt these allies to demand a much larger commitment of U.S. conventional forces for their defense. The cost savings of abandoning first use are not as straightforward as they might seem.

Even if removing tactical weapons from Europe resulted in a net savings for the United States, it is not clear that making U.S. commitments cheaper would produce the desired policy outcome, i.e. the deterrence of U.S. adversaries. To the extent that the use of a nuclear weapon against a nuclear-armed opponent could be extremely costly for the United States, the nuclear threat may be more effective in deterring the adversary than a low-risk commitment of conventional forces.  Removing tactical nuclear weapons and placing the U.S. nuclear force on a lower state of alert could also prove extremely dangerous if the United States subsequently reversed these decisions for any reason. An opponent may interpret such reversals as signs of an imminent attack and choose to strike the United States before it has a chance to act.

There may be other benefits for the United States in keeping first use on the table. Including the possibility of first use in official U.S. doctrine requires the military to make concrete plans for how it would incorporate nuclear weapons into actual operations. Even if we hope that the United States would never launch a first strike, the possibility that it might happen some day means that the military cannot afford to be unprepared for how to execute such a strike and for how to mitigate the consequences for U.S. forces if tactical nuclear weapons were used on the battlefield.

On the other hand, there may be considerable moral benefits to the abandonment of first use.  Publicly committing to the use of nuclear weapons only in response to a nuclear attack could help the United States to reinforce its desired status as a moral leader in the international system and might give it more legitimacy in negotiations with potential proliferators. Eliminating the U.S. nuclear arsenal in its entirety is neither wise nor feasible (a sentiment with which President Obama evidently agrees, despite his commitment to “global zero” early in his tenure).  Relegating these weapons to the sole role of deterrence in U.S. doctrine might, however, encourage other states to do the same and might delegitimize the pursuit of these weapons by new states.

Never First Use?

No one wants to imagine a world in which the United States would use nuclear weapons against an opponent again, but the first-use doctrine may provide some benefits to the United States and its allies. Whether those benefits outweigh the costs of retaining first use depends on whether we believe that the nuclear threat is an effective deterrent to U.S. adversaries and whether we believe that nuclear weapons could be employed in combat in a limited way. If we think that the Korean scenario makes sense—a first strike against North Korea’s nuclear facilities to prevent it from using its own weapons in an imminent attack on South Korea—then retaining the first-use doctrine makes sense. If, on the other hand, we believe that any threatened or actual use of nuclear weapons—even a limited attack against a weak adversary like North Korea—could invite escalation to devastating retaliatory nuclear exchanges, then renouncing first use may be desirable.

It is difficult to believe that the United States’ allies would not view the elimination of the first-use doctrine as a threat to their own interests. Nor is it clear how the United States would beef up its conventional deterrents given the public’s low tolerance for military spending and the fact that U.S. forces are already overcommitted and exhausted by fifteen years of war. Until the scope of American interests narrows or the American public is willing to cough up more money and personnel to reinforce U.S. commitments overseas, the best way to secure U.S. interests may be to maintain the possibility of first use while hoping that it will never be implemented.

Dianne Pfundstein Chamberlain, PhD, is an Associate Research Fellow with the Saltzman Institute of War and Peace Studies at Columbia University. She was formerly an Assistant Professor in the Department of Political Science at the University of Massachusetts, Amherst, and a Postdoctoral Research Fellow in the International Security Program at the Belfer Center for International Affairs, Harvard Kennedy School. She is the author of Cheap Threats:  Why the United States Struggles to Coerce Weak States (Georgetown University Press, 2016).

Image: Tech. Sgt. Timothy Cotterall is decontaminated following attempts to identify multiple biological contaminants in a simulated lab. Flickr/U.S. Air Force