at the time) should the USSR deploy any kind of nuclear weapon against civilian targets. A revolution in thinking occurred with the introduction of the intercontinental ballistic missile (ICBM), which the Soviet Union first successfully tested in the late 1950s. To deliver a warhead to a target, a missile was far less expensive than a bomber that could do the same job. Moreover, at the time it was impossible to intercept ICBMs due to their high altitude and speed. In the 1960s, another major shift in nuclear doctrine occurred with the development of the submarine-based nuclear missile (SLBM). It was hailed by military theorists as a weapon that would assure a surprise attack would not destroy the capability to retaliate, and therefore would make nuclear war less likely. The Cold War Since the end of WWII, no industrial nations have fought such a large, decisive war, due to the availability of weapons that are so destructive that their use would offset the advantages of victory. The fighting of a total war where nuclear weapons are used is something that instead of taking years and the full mobilisation of a country's resources such as in WWII, would take tens of minutes. Such weapons are developed and maintained with relatively modest peace time defence budgets. By the end of the 1950s, the ideological stand-off of the Cold War between the Western World and the Soviet Union involved thousands of nuclear weapons being aimed at each side by the other. Strategically, the equal balance of destructive power possessed by each side situation came to be known as Mutually Assured Destruction (MAD), the idea that a nuclear attack by one superpower would result in nuclear counter-strike by the other. This would result in hundreds of millions of deaths in a world where, in words widely attributed to Nikita Khrushchev, "The living will envy the dead". During the Cold War, the superpowers sought to avoid open conflict between their respective forces, as both sides recognized that such a clash could very easily escalate, and quickly involve nuclear weapons. Instead, the superpowers fought each other through their involvement in proxy wars, military buildups, and diplomatic standoffs. In the case of proxy wars, each superpower supported its respective allies in conflicts with forces aligned with the other superpower, such as in the Korean War, the Vietnam War, and the Soviet invasion of Afghanistan. Milestones See also Mobilization