Samenvatting

The concept of deterrence has dominated Western strategic thought for some seven decades. It shows no signs of easing its grip. In the face of any new security threat, such as terrorism or cyber-attacks, one of the fi rst questions to be asked is ‘ can this be deterred? ’ Even when the answer is not very encouraging the inclination is to persevere until some way is found at least to reduce if not remove the threat through some form of deterrence. This may have less to do with deterrence ’ s reliability or effectiveness as a strategy and more because of its inherent normative appeal. When a state adopts a deterrence strategy it signals that it does not seek a fi ght but still considers some interests to be so vital that they are worth fi ghting for. It implies a defensive intent without weakness. It seeks to prevent aggression while being non-aggressive. It sustains rather than disrupts the status quo. For these reasons, it has positive associations that other potential strategies lack. Appeasement as a deliberate strategy has been discredited since the 1930s; conquering other states is now seen to be as demanding as it is illegal. There is no dishonour in deterrence. The main objections to deterrence strategies are because they provide the core rationale for possessing nuclear weapons. Those arguing for nuclear abolition often argue that the deterrence effect is a chimera. What were thought to be deterrent successes either had other causes or could be achieved by other means. This can lead to playing games with history to make a point. It was of course entirely possible that there would have been no Third World War even if nuclear weapons had never been invented but in the post-1945 world at crucial points nuclear weapons acted as a vital source of restraint. 1 A stronger, more moderate argument is that nuclear deterrence was a thin reed upon which to rely and might have let governments down at crucial moments. But that was an argument about the limits of deterrence and not its potential validity. There is nothing effortless about deterrence. It demands close attention to how threats are designed, conveyed and, if necessary, implemented. The concept itself is simple enough. Deterrence occurs when A persuades B not to take a speci fi ed step by convincing B that whatever the anticipated gains the likely costs will be higher. When A issues a threat, its effectiveness will depend on B ’ s perception of what it might mean as much as A ’ s intent. If B does not take A ’ s threat seriously and concludes that it can be safely ignored then deterrence will fail. Or A may fail to deter through negligence. It knows that B needs deterring but does not realise exactly what B is up to until too late and so is caught by surprise. Once A needs to retrieve a lost position deterrence has become irrelevant. The tables may be turned as B is now deterring A to preserve a new status quo. Nor is there a standard formula suitable for application in any situation where deterrence is required. What might work when vital interests are involved might not work when the stakes are low. A ’ s stern threats might hit home when B is paying attention but miss completely when B is distracted or if there is a lot of background noise. What worked last time might not work this time, not least because B knows what to expect. And, as deterrence depends on the status quo holding, when nothing much changes can we be sure that this is because of the deterrent threat? Is that why B has held back? Perhaps no hostile action was ever intended. Or if it has not happened that might be for reasons unrelated to deterrence. Deterrence is therefore simple in principle and a natural strategy to adopt but it is not so straightforward when it comes to implementation. It poses both a conceptual and a practical challenge.