and in the responses of the United States to those developments, which will profoundly affect the need for deterrence strategies and nuclear weapons, and the wisdom of further nuclear disarmament. We believe that this uncertainty means proceeding cautiously; we conclude that nuclear weapons should retain an attenuated, but still important, role in U.S. national security policy for the time being.
It is widely agreed today that "deterrence" as a term of art means preventing war either through fear of punishment or fear of defeat, or sometimes even through fear of undefined negative consequences. The word "deterrence" is derived from the Latin de + terrere, literally "to frighten from" or "to frighten away." Thus, fear is central to the original meaning of deterrence. The idea that vast, indiscriminate, and unacceptable damage would be inflicted in retaliation for aggression, as was associated with the prospect of the aerial bombing of open cities in the 1930s, or the employment of nuclear weapons since World War II, has long been central to the popular understanding of the term deterrence. That fear of defeat could be powerfully deterring, although a longstanding idea, has been less widely understood.
Nuclear deterrence both as a concept and as practical doctrine had several variations during the Cold War. These included the declared doctrine of massive retaliation, with its stark punitive threat and heavy reliance on the strategic nuclear air offensive. The mature U.S. nuclear strategy, which obtained from the 1960s until the collapse of the Soviet Union, was extended nuclear deterrence. Under this doctrine, the United States deterred direct attack upon itself with strategic nuclear forces, while extending protection to its Cold War allies and friends by promising to escalate a war to the nuclear level if they were in danger of defeat by Soviet-led forces, even if this entailed first use of nuclear weapons by the United States. Extended deterrence was achieved via the "seamless web" of conventional, theater, and strategic nuclear forces. Although this strategy did have an important conventional component, it ultimately depended on the threat of escalation to large-scale nuclear use. One interesting late variation on the theme of extended nuclear deterrence was that the fear that deterred could be a threat to destroy not urban-industrial areas per se but those items the opposing regime valued most. In the case of the Soviet Union, this was postulated to be the survival of the regime itself and its ability to preserve and perpetuate its control over the Soviet state. Another variation was that deterrence could be strengthened by posing the threat that the Soviets' strategic nuclear strike would not succeed because of the operation of U.S. strategic missile defenses, especially if linked to the prospect for subsequent punishment. It is also true that the idea of deterrence was subsumed within a system of mutual deterrence because of the deployment of large-scale Soviet nuclear forces in the 1950s and 1960s. However, neither mutuality nor parity is a necessary or inherent characteristic of the concept of deterrence.