Richard Fernandez reflects on the nature of deterrence. It’s crucial, he observes, to create uncertainty in the mind of the enemy.
The key concept embodied in the Essentials of Post-Cold War Deterrence is the idea that it rests on an American commitment to inflict an unspecified but devastating response upon any nation or group that attacks it. In order to prevent any adversary from legalistically parsing a pre-announced set of conditions under which the United States would retaliate, all the terms were left intentionally vague so that only American national command authority could say with certainty what would happen next. In the words of the document:
While it is crucial to explicitly define and communicate the acts or damages that we would find unacceptable and, hence, what it is that we are specifically seeking to deter, we should not be very specific about our response. It is however, crucial that the level of our commitment to the things we value be unfaltering, and that the adversary have little doubt of this. Without saying exactly what the consequences will be if the US has to respond, whether the reaction would either be responsive or preemptive, we must communicate in the strongest ways possible the unbreakable link between our vital interests and the potential harm that will be directly attributable to anyone who damages (or even credibly threatens to damage) that which we hold of value.
This has the effect of threatening a vastly disproportionate response towards any attempts at aggression by strategic inferiors. While a proportionate response is not ruled out, neither — and this is the essential point — is a wholly disproportionate one. Under such a doctrine a missile defense capability would play a very important role: it would greatly increase the potential lopsidedness of the exchange. Time and again the Essentials of Post-Cold War Deterrence emphasizes the idea that one of key goals of modern defense is to instill uncertainty in the minds of an adversary — whether that opponent is rational or not.
Now this raises an interesting issue. Just war theory, in its currently most popular form, insists on proportionality. But the effectiveness of deterrence depends on the possibility of a disproportionate response, that is, a response that violates just war theory. So, if you commit yourself to just war theory, and your commitment is believed by your enemy, you actually make war more likely by undermining the effectiveness of your own deterrence. In short, committing yourself to do the right thing (by just war theory’s lights, anyway) may be the wrong thing to do.