Stephen M. Walt

Rethinking the “nuclear revolution”

Ever since graduate school, I’ve been a firm believer in the "nuclear revolution." The term refers to the belief that the invention of nuclear weapons constituted a fundamental shift in the nature of warfare, and conceivably in international relations itself. As Bernard Brodie put it in The Absolute Weapon (1946): "Thus far the chief purpose ...


Ever since graduate school, I’ve been a firm believer in the "nuclear revolution." The term refers to the belief that the invention of nuclear weapons constituted a fundamental shift in the nature of warfare, and conceivably in international relations itself. As Bernard Brodie put it in The Absolute Weapon (1946): "Thus far the chief purpose of our military establishment has been to win wars. From now on its chief purpose must be to avert them." (Hmmm. Given that we’ve fought at least five significant wars since World War II, and a host of minor conflicts, we don’t seem to be following Brodie’s advice).

The idea of the "nuclear revolution" goes further than that, however. As refined by scholars like Brodie, Thomas Schelling, Glenn Snyder, Robert Jervis, Kenneth Waltz, and Stephen Van Evera, nuclear weapons are said to provide states with the ability to protect their sovereignty and independence not via direct defense but rather through deterrence. Instead of defending one’s borders or vital interests with conventional military forces, states could deter enemy attack by threatening to inflict unacceptable damage on an aggressor. As long as they possessed a secure second-strike retaliatory force, in short, they could deter attack by threatening to make an aggressor’s losses outweigh its gains. As Winston Churchill famously put it, peace had become "the sturdy child of terror, and survival the twin brother of annihilation."

Finally, as Jervis argued in several important works, the nuclear revolution dampened (and maybe eliminated) the security dilemma between states. As long as a state possessed a secure second-strike capability (SSC), its security wasn’t affected if an possible adversary had a much larger arsenal. In the world of mutual assured destruction, in short, "nuclear superiority" was a meaningless concept. Even if an enemy had a lot more warheads, it couldn’t attack a state with a secure SSC without risking devastating retaliation. And it didn’t take a genius to figure out that even a minor nuclear exchange would ruin your whole day.

According to the logic of the "nuclear revolution," therefore, states with second-strike capabilities were secure against attack and didn’t need to worry very much about their sovereignty or independence. The "security dilemma" was muted, and cooperation between states would be greatly facilitated. (Other theorists took this argument even further, and suggested that the technological change embodied in the nuclear revolution heralded the end of the nation-state and the emergence of a global republic).

I’ve long accepted the core tenets of this basic argument, and I’ve taught it to my students for years. But lately I’ve started wondering about just how far-reaching this "revolution" really was. Although I still accept the core logic, the existence of nuclear weapons doesn’t seem to have had the far-reaching political effects that Jervis and others anticipated. 

Consider: the United States has a very large and sophisticated nuclear arsenal, and a very secure "second-strike" capacity.  It could easily devastate any country foolish enough to attack us. Yet the United States also maintains a large and expensive Navy, a sizeable and expensive air force, and significant ground and amphibious too. And the justification for this is not the need to defend human rights, or even spread democracy (though both claims get invoked from time to time); rather, we maintain these forces because we think they are essential to our national security. 

Yet if nuclear weapons were somehow disinvented, it is not obvious that this event would have any discernible effect on our conventional military posture, especially given the absence of a true "peer competitor." And if China continues to grow and expands its own military capabilities, will the existence of our robust nuclear arsenal make us indifferent to this development? I rather doubt it.

And it’s not just the United States that seems to have so little confidence in its own deterrent. Israel has by most accounts a sizeable nuclear arsenal of its own, and a clear "second-strike capability" against any possible foe. Yet Prime Minister Benjamin Netanyahu recently warned about future threats along Israel’s "Eastern front," a position linked to the demand that a future Palestinian state be demilitarized and that Israel retain control of the Jordan River Valley. Israel developed nuclear weapons to enhance its security (a perfectly understandable decision), but having the bomb hasn’t made it feel any safer or reduced its perceived security "requirements," even against conventional military forces.

One can go further. Russia has the second-largest nuclear arsenal in the world, but that hardly precludes it from maintaining large conventional forces and from striving for regional influence around its borders. Nobody could invade Russia today without risking devastating retaliation, yet the "security dilemma" seems to be alive and well in the minds of Russian leaders. One could say much the same for both India and Pakistan — each tested nuclear weapons in order to enhance their security, yet the security competition between the two states has not declined by as much as the "nuclear revolution" thesis suggests.

In short, although a number of countries have acquired nuclear arsenals, and several have large and redundant nuclear forces, the security dilemma has not disappeared and national leaders don’t seem to be reducing their defense requirements because they have great confidence in the deterrent power of these awesome weapons.

Don’t get me wrong: I’m not suggesting that nuclear weapons have no effects whatsoever, and I’m not a sudden convert to the idea of general and complete disarmament. Unlike John Mueller, for example, I believe the presence of nuclear weapons was one of the factors that kept the Cold War from heating up. If nothing else, having a nuclear arsenal helps ensure that other nuclear (or WMD)-armed states don’t attack you directly, and it may even provide a "nuclear umbrella" over close allies. But nobody in power seems to think that a nuclear deterrent is sufficient to protect the country, or even to significantly reduce other defense or security requirements.

The lesson I draw from this is that nuclear weapons have very limited value. A handful of survivable weapons makes it very unlikely that another state will attack you directly or try to invade and take over your country. That’s about it. And states certainly don’t need thousands of warheads in order to obtain these effects.  In short, if we’re going to keep spending a lot of money on conventional forces and conducting geopolitics much as we did before 1945, we might as well save some money and move to a "minimum deterrence" posture, like this. And by acknowledging that nuclear weapons are neither the be-all and end-all of international security or a potent talisman of great power status, we might make it easier for potential entrants into the nuclear club to decide that it’s not worth the trouble or the cost.

Stephen M. Walt is the Robert and Renée Belfer professor of international relations at Harvard University.

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