The Long Nuclear Peace

Making a positive case for nuclear weapons is a relatively lonely business. In the late 1990s, many longed to end the threat of nuclear weapons, either through some form of ballistic missile defense, or by banning them entirely. Tom Clancy was perhaps the most popular writer who depicted a world where this was possible, but many other works of popular culture probably helped stir opposition to them as well. For reasons both emotional and practical, the dream of nuclear abolition continues apace with significant scholarly and popular support. Put simply, nukes aren’t popular.

In his most recent book, The Logic of American Nuclear Strategy, Matthew Kroenig suggests that debates over nuclear weapons offer the closest thing to America’s culture wars that international relations can boast, occasioning more blind faith and intense passion than any other subject in the field. Many international relations scholars usually deny that having a nuclear deterrent above and beyond a functional second-strike capability (that is, the secure ability to retaliate against an adversary after their strike hits) is useful, yet policymakers often behave otherwise. Others such as John Mueller believe that they are irrelevant to the conduct of international relations entirely. Some fear brinksmanship and escalation, while others see these practices as vital elements of diplomacy.

And yet there are some loose lines of agreement between the various camps. Scholars largely (and perhaps sometimes begrudgingly) accept that nuclear weapons have brought an end to great power war. Among both international relations realists and liberals there is some general acceptance that growing nuclear arsenals or the spread of these weapons is deeply destabilizing, and that stability above all is key to maintaining peace. One might add other items to this list, but the disagreements about precisely why and how we have gotten to this point are violent and deep.

Kroenig seeks to change the terms of these debates by claiming that nuclear weapons don’t just deter conventional war—they give nuclear states greater influence in the world. Most experts simply claim that those who believe this are wrong or illogical, but Kroenig argues that:

military nuclear advantages beyond a secure, second-strike capability can contribute to a state’s national security goals. This is primarily because a robust nuclear force reduces a state’s expected cost of nuclear war, increasing its resolve in high-stakes crises, providing it with coercive bargaining leverage, and enhancing nuclear deterrence.

The book proceeds systematically through these assumptions, attempting a logical demonstration that a great deal of what educated people think they know about the prospect of nuclear war either distorts reality or is simply mistaken, and that the relative size of the U.S. nuclear arsenal matters far more than scholars assume.

Throughout the Cold War, observes Kroenig, generalizations about Mutually Assured Destruction vastly overestimated the destructive effects of the Soviet and U.S. nuclear arsenals. Scholars reasoned that war would be apocalyptic, and to some degree this left them unable to think seriously about how to construct a nuclear strategy that would not just deter war, but also better protect the United States in the event one actually came to pass.

Kroenig suggests that large numbers of scholars and journalists found themselves too possessed by fear to think logically about the strategic challenges nuclear weapons pose. Indeed, one of the more surprising facts about much of the literature on the subject is that the authors so often “refrain from writing, talking, or even thinking about nuclear war” itself, and focus entirely on the concept of deterrence. It isn’t hard to imagine why this is a natural line of reasoning for them: nearly all of America’s best universities are in cities that top Russian and Chinese targeting lists, and even if the rest of the country survived a nuclear exchange, the city-driven culture in which we live might be utterly destroyed.[1]

While Kroenig is careful not to minimize the catastrophe any nuclear exchange would bring with it, he observes that in a nuclear contest, reducing an enemy’s arsenal makes a substantial difference in the life or death of one’s own people. Part of the logic here is that the United States uses what is called a “counter-force” strategy. That is, the U.S. nuclear arsenal would target key enemy nuclear facilities, bases, and support structures rather than be held to threatening the entire enemy population. Because of this emphasis, more warheads relative to the enemy leads to lower casualties because fewer of the enemy’s arsenal would survive to launch an attack. On one level this seems obvious, and Kroenig convincingly demonstrates why this is true.

The book grows less convincing on the subject of how nuclear weapons allow states to achieve other goals. It makes intuitive sense that having nuclear weapons would immunize a state from threats of invasion, but the debate seems far from settled on how far their coercive power goes. Much has already been written by specialists about Kroenig’s empirical claims on this score (for a few examples see here, here, and here), but as I read, I kept wondering what should we think about the morality of his claims, as well as their broader implications for how we think about grand strategy.

Thinkers in the Just War tradition generally focus on how nuclear weapons violate key tenets of justice—in particular, that they make it impossible to discriminate between combatants and innocents. Thus, such scholars tend to either argue for the complete abolition of an intrinsically evil means of war (think here of the U.S. Conference of Catholic Bishops’ famous 1983 pamphlet, The Challenge of Peace), or suggest, as Michael Walzer does in Just and Unjust Wars (first published in 1977, with a 5th edition in 2015), that “nuclear weapons explode the theory of just war.” For Walzer, the trouble with nuclear weapons is:

that they make hostages of us all, albeit ones who lead more or less normal lives….Supreme emergency has become a permanent condition. Deterrence is a way of coping with that condition… and there may be no other that is practical in a world of sovereign and suspicious states…. Nuclear war is and will remain morally unacceptable, and there is no case for its rehabilitation. Because it is unacceptable, we must seek out ways to prevent it, and because deterrence is a bad way, we must seek out others.

Many scholars suggest something similar, and agree that Just War theorizing cannot usefully function in such horrifying terrain.

And yet, even the most hardened international relations realist cannot help thinking in at least implicitly moral categories, usually framed in terms of prudence. Kroenig observes that “while even a single nuclear weapon detonated in the United States would be a tragedy of historic proportions, it is also the case that twenty nuclear detonations would be worse. And fifty would be worse still.” Perhaps it is simply true that under this sort of pressure, moral analysis always collapses fine categories into the murky terrain of greater and lesser evils, or even less helpfully, the crude comparison of casualties.

Many would like to see nuclear weapons banned. But even here, we should think seriously about the alternatives. Contemplating nuclear strategy requires discomfort to be sure, yet it is important to consider the actual alternatives to them. Moral seriousness here requires we think of the world in which we actually live—one where states seek the power to coerce. So this leaves us with a question: Would a world without nuclear weapons be a better one?

Such a world might remove one diffuse moral challenge (that of Walzer’s justice-exploding blanket coercion) only to replace it with a much more dangerous and competitive environment between states. Even if Nina Tannenwald and others are right that there is a “nuclear taboo,” the absence of nuclear weapons would greatly decrease the costs of great power war, and by extension, incentivize the return of pre-1945 international politics.

Kroenig offers a reminder that deterrence is better than war, and to be effective at deterrence, one must 1) engage in some level of strategic risk to maintain an arsenal that genuinely holds adversaries in peril, and 2) think seriously about how to deploy that deterrent. Those who yearn for a reduced U.S. role in the world, and the vastly reduced defense budgets that might come with it, are often are hazy on what this would actually take. Only nuclear weapons make such a reduction possible, because they offer strategists a clear path to deterring aggression without needing to deploy large conventional forces around the world.

Prudence sometimes dictates that we contemplate the unthinkable, if only to keep it at bay.