One thing that is already clear about the future, is that deterrence will remain a pivotal goal of U.S. strategy toward Iran and other potential foes.
The cost of armed conflict against these adversaries are high, policymakers will look for ways to protect American interests without engaging in open warfare. In this context, it is useful to step back and take a larger look at deterrence and how it works.
The Department of Defense defines deterrence in similar, yet more specific, terms as “The prevention from action by fear of the consequences. Deterrence is a state of mind brought about by the existence of a credible threat of unacceptable counteraction.” Simply put, deterrence occurs when one can make an adversary believe that the consequences of behaving undesirably will outweigh the benefits.
Yet as history has shown, deterrence often fails; adversaries attack.
So what separates deterrence successes from these failures? The key is to establish the credibility of deterrent threats. That is to say, one must be able to instill a sincere belief in adversaries that the promise of counteraction will be carried out if they fail to comply with the threat.
Concerns about credibility are manifest in the actions that governments take to establish it. In large part, these strategies are consistent with advice provided by the Roman strategist Vegetius, who wrote, “Si vis pacem, para belum”; if you desire peace, prepare for war.
His premise was simple. A powerful military would have a greater chance of deterring an adversary from taking an undesirable action than a weaker military, because a stronger military could more easily punish a potential aggressor. Vegetius’ point is no less valid today than it was almost 2,000 years ago. The United States, for example, develops powerful weapons like tanks, aircraft carriers, and fighter aircraft not in the hope that it will have an opportunity to use them, but rather in the hope that their visible existence will deter adversaries from threatening our interests.