Cheryl of Whirled View kindly indicated that continued posts on the future of US nuclear strategy from national security bloggers were still welcome. Therefore, I'll throw in a couple of my own observations on this topic, starting with a few words about compellence.
In a widely-cited Harvard Business Review article, Michael Porter pointed out that strategy includes explicit choices about what you don't do. While not everything in Porter's article applies equally to corporations and governments, that statement certainly does. When the choice involves nuclear weapons, the consequences of what you do and don't do are, of course, potentially cataclysmic.
Early questions about compellence
For the first two or three decades that the United States possessed a nuclear arsenal, American nuclear strategists tried to figure out whether these fearsome weapons could be used not just for deterrence, but compellence. In less academic terms, you might summarize the question as, "Hey, if we have nuclear weapons, and lots of other countries don't, can't we use the nuclear threat to bully them?" Surprisingly, the answer appears to be, "No."
Thomas Schelling, whose landmark book Arms and Influence is the inspiration for the name of this blog, was one of many strategists who approached this question in the abstract. Sometimes, the tools of inquiry were analogies, such as Schelling's famous metaphor of the game of chicken. At other times, the tools were more quantitative, such as the complex mathematical projections of missiles, megatons, and mass casualties, to think as objectively and precisely as possible about, as Herman Kahn called it, "the unthinkable."
The analysts at the RAND Corporation and the Defense Department engaged in this research found many ways to deter a Soviet nuclear attack. They did not, however, find any sure-fire ways to use the US nuclear arsenal to blackmail the Soviets, Chinese, or even the many countries that lacked nuclear weapons of their own into taking actions they might otherwise resist. In other words, nuclear weapons could stop the other superpower from doing something; it was much, much harder to devise techniques to compel other governments to acquiesce to American wishes.
History belies theory
Historical experience also indicated that compellence was, perhaps, a pipe dream. The United States chose not to use nuclear weapons against the North Koreans and North Vietnamese. Just as importantly, the US did not make serious, consistent threats of nuclear attack, if these two adversaries did not halt their aggression against their southern neighbors. In other Cold War confrontations in which the other side lacked nuclear weapons--for example, the Arab-Israeli wars--US leaders largely kept the nuclear threat in its sheath.
The exceptions looked more like deterrence, but on a smaller scale. For example, the US went to a high degree of nuclear alert in 1973 to make it clear to the USSR that any Soviet military intervention in the Yom Kippur war. The Eisenhower gave the People's Republic of China a clear glimpse of the American nuclear threat during the Quemoy-Matsu crisis. Again, the goal was more deterrence--stopping the Chinese from expanding the conflict beyond the two disputed islands to Taiwan--and less compellence.
Why did compellence turn out to be a mirage? Only part of the answer depended on the unique balance of power mechanics of the Cold War. Both superpowers were wary of nuclear threats, for fear that the other superpower might get involved in the conflict, raising both the stakes and unpredictability of any conflict. The WWI-like escalation spiral, from regional crisis to global war, haunted both theorists and practitioners of nuclear diplomacy.
However, the fear of escalation was hardly the only reason why compellence practically disappeared from US national security policy. The credibility of the threat was questionable whenever US cities were not directly at stake. Just as Hitler once wondered, "Who would die for Danzig?" American leaders asked, "Who would believe us if we threatened nuclear attack over the Soviet repression of Hungarian independence?"
The credibility of nuclear threats is always the most valuable part of having a nuclear arsenal. Otherwise, nuclear weapons are only useful by actually using them, which is the worst of all possible scenarios. Compellence, on the other hand, degrades the currency of US nuclear threats, since the stakes are far lower for the United States than the "nightmare scenario" of classic deterrence.
The psychology of international relations creates additional obstacles to successful compellence. Deterrence normally stops actions that have not been started at all. The other side loses practically nothing for backing down, since nothing has happened. In many situations, such as the Clinton Administration's threats against North Korea, no one outside the two governments involved might be aware that a crisis has been happening at all.
The threat, in these less dire circumstances, is not credible because no one believes that US leaders are either immoral or irrational enough to unleash mass carnage. That, too, is an important part of the credibility of US power and influence.
Compellence, on the other hand, often requires the embarrassment or humiliation of the other side. Not only do the scenarios often start with public statements or actions (for example, "Disarm immediately, or else"), but the adversary may want to publicize US nuclear threats, to make its cause more sympathetic in the face of American bullying.
Nuclear power, but no leverage
The end of the Cold War, therefore, has not improved the opportunities for nuclear compellence. No modern-day John Foster Dulles will find an updated version of the "massive retaliation" doctrine any more successful than it was in the 1950s.