Western governments have become preoccupied with preventing mass-casualty terrorism. The American-led campaign against al Qaeda has shown that the preventive strategies most likely to succeed must focus on disrupting and destroying suspect groups and their capabilities. Indeed the emphasis of the Bush administration on preemption as a central pillar of emerging U.S. strategic doctrine indicates that this approach is the best way to deal with chemical, biological, radiological, nuclear, or enhanced high explosive (CBRNE) weapons. While active disruption and destruction constitute the most realistic options at hand, does this mean that deterrence has nothing to offer as an element of a broader, comprehensive strategy for preventing mass-casualty terrorism?
An Established Strategy
The object of deterrence is preventing real or potential enemies from initiating hostile acts. It differs from but is related to the concept of compellence--more often known as coercion--where the goal is getting an enemy to do something--to alter its behavior and an existing state of affairs. For example, air strikes by the United States against Libya in 1986 were intended in part to compel Colonel Qaddafi to stop sponsoring terrorist activity against American targets in Europe. The aim was changing Libyan policy, under which the regime sponsored terrorism, not preserving it.
A deterrent strategy can rely on one or both of two mechanisms. First, it can be based on threats to visit punishment on an enemy that significantly outweighs the gain of a particular course of action. This approach is traditionally viewed as targeting civilian assets and constituted the basis of the Cold War concept of mutual assured destruction.
Another approach is based on the concept of denial. Specific capabilities deter enemies from pursuing either a given objective or a conflict strategy. This is achieved by undermining their ability, or belief in their ability, to realize a desired outcome.
Deterrent strategies can include both punishment and denial mechanisms. For example, the United States appears to favor such an approach to deter unconventional weapons usage by a regime by combining denial capabilities like missile defenses with the threat of punishment. Both mechanisms may support a comprehensive strategy to prevent mass-casualty terrorism.
A credible deterrent posture requires the capability to deliver on the deterrent message, or at least the appearance of it. The deterrer must demonstrate the intent and resolve to fulfil the message and effectively communicate this to an enemy, including which lines not to cross.
Deterrence also assumes that a target will be a cost-benefit calculator--a rational actor who evaluates options in terms of costs and benefits, including likely responses. But what is accepted as rational by one actor may not appear rational to another because of cultural factors or decisionmaking processes. This is a major consideration in the war on terrorism because of the asymmetric nature of the opposing sides in almost every respect. A preventive strategy in this context--deterrent or other--requires knowing enemy motives, worldview, resolve, capabilities (including conflict strategies and techniques), and vulnerabilities.
Measuring the failure of deterrence is straightforward because the action that the deterring party seeks to avoid occurs. However, measuring success is more difficult, as it cannot be proven that the strategy was pivotal, marginal, or irrelevant to why an enemy opted not to act. This can be significant when attempting to prevent mass-casualty terrorism.
What role might deterrence play in preventing catastrophic terrorist attacks? How might such a strategy fit into broader counterterrorist policies? Should the aim be preventing actions that could create mass casualties or specific types of attack? Should the objective be preventing conflict escalation over a determined threshold (something that is hard to define) or buying time in order for preventive approaches to take effect? …