Deterrence

Deterrence, in international relations, the policy of discouraging hostile action by a potential aggressor. Although deterrence may occur unintentionally, the term most commonly denotes deliberate efforts to prevent the initiation of aggression. Such an effect can be achieved either by convincing a would-be aggressor that the attack will fail—“deterrence by denial”—or by giving the impression that success would be achieved at an excessive price—“deterrence by punishment.” Punishment may be imposed either by mounting an effective defense or by launching retaliatory attacks.

Deterrence is possible in any situation of relative military balance and is by no means a modern phenomenon. However, making deterrence a calculated and explicit policy of defense did not become a common strategy until the 20th century. One notable example occurred in the early 1900s when German admiral Alfred von Tirpitz based his naval strategy on the theory that Great Britain would hesitate to fight even an inferior German navy if the losses incurred would leave the British Navy inferior to other rivals.

The introduction of nuclear weapons in the 1940s raised deterrence to a new level of strategic thinking. Three chief features of nuclear weapons account for this change: (1) effective defense against massive nuclear attacks is virtually impossible—thus, safety can be achieved only by averting an attack; (2) the destructive power of nuclear weapons amplifies the threat of retaliation by nations who possess such weapons; and (3) the scale of destruction achievable in a nuclear retaliation can greatly exceed the value of any gains likely to be achieved by the initial attack.

Deterrent strategies were utilized during the Cold War, an intense ideological struggle that began shortly after 1945 between the United States and the Union of Soviet Socialist Republics (USSR). The U.S.-backed North Atlantic Treaty Organization (NATO) had substantial nuclear weapons capability but was thought to be inferior in conventional military capacity. Consequently, threatening nuclear retaliation was considered a good way to deter conventional as well as nuclear aggression. Under President Charles de Gaulle, France adopted a national policy of dissuasion by which it hoped a small nuclear force would deter any attack the USSR might consider.

As time passed, strategists recognized that even nuclear deterrence presented difficulties. It would work only if the threat to retaliate was credible. Credibility required both the physical capacity to retaliate and the perceived will to do so. This led to efforts to make the retaliatory forces invulnerable to a first strike, by putting missiles in hardened silos or hidden submarines to assure the ability to retaliate.

Although the end of the Cold War brought an end to the era of global nuclear deterrence, deterrence remains a central concept to strategic thinking. In regional conflicts, the United States has relied on conventional deterrence—threatening an overwhelming conventional attack—to prevent aggression. For example, the United States maintains thousands of troops in South Korea to deter North Korea from invading South Korea. However, effective deterrence only works against states or groups that fear the consequences of retaliation. Suicidal states or groups cannot be deterred—they are willing to suffer severe punishment or death in response to an attack, so threats of punishment are rendered meaningless.

Following the devastating terrorist attacks of September 11, 2001, President George W. Bush committed the United States to a policy of preemptive war—the use of force to attack potential threats before they are able to fully threaten the United States. This policy, known as the Bush doctrine, moved the United States away from its traditional reliance on deterrence as a military strategy by instead advocating preemption. Despite this policy shift, the concept of deterrence is likely to remain central to military strategy.