In the event of an attack from an aggressor, a state would massively retaliate by using a force disproportionate to the size of the attack.
The aim of massive retaliation is to deter another state from initially attacking. For such a strategy to work, it must be made public knowledge to all possible aggressors. The aggressor also must believe that the state announcing the policy has the ability to maintain second-strike capability in the event of an attack. It must also believe that the defending state is willing to go through with the deterrent threat, which would likely involve the use of nuclear weapons on a massive scale.
Massive retaliation works on the same principles as mutual assured destruction (MAD), with the important caveat that even a minor conventional attack on a nuclear state could conceivably result in all-out nuclear retaliation. However at the time when massive retaliation became policy, there was no MAD, because the Soviet Union lacked a second strike capability throughout the 1950s.
In August 1945, towards the end of the Pacific theater of World War II, the United States delivered nuclear attacks on Hiroshima and Nagasaki in Japan. Four years later, on August 9, 1949, the Soviet Union developed its own nuclear weapons. At the time, both sides lacked the means to effectively use nuclear devices against each other. Eventually with nuclear triads being established, both countries were quickly increasing their ability to deliver nuclear weapons into the interior of the opposing country.
The term "massive retaliation" was coined by Eisenhower administration Secretary of State John Foster Dulles in a speech on January 12, 1954.
We need allies and collective security. Our purpose is to make these relations more effective, less costly. This can be done by placing more reliance on deterrent power and less dependence on local defensive power... Local defense will always be important. But there is no local defense which alone will contain the mighty landpower of the Communist world. Local defenses must be reinforced by the further deterrent of massive retaliatory power. A potential aggressor must know that he cannot always prescribe battle conditions that suit him.
Dulles also said that the U.S. would respond to military provocation "at places and with means of our own choosing." This speech and quotes appear to form the basis for the term massive retaliation, which would back up any conventional defense against conventional attacks with a possible massive retaliatory attack involving nuclear weapons.
The doctrine of massive retaliation was based on the West's increasing fear at the perceived imbalance of power in conventional forces, a corresponding inability to defend itself or prevail in conventional conflicts. By relying on a large nuclear arsenal for deterrence, President Eisenhower believed that conventional forces could be reduced while still maintaining military prestige and power and the capability to defend the western bloc.
Upon a conventional attack on Berlin, for instance, the United States would undertake a massive retaliation on the Soviet Union with nuclear weapons. The massive response doctrine was thus an extension of mutually assured destruction to conventional attacks, conceivably deterring the Soviet Union from attacking any part of the United States' sphere of influence even with conventional weapons.
Two members of the RAND Corporation criticized the doctrine as too aggressive and identical to the first strike. Herman Kahn stressed that many military planners adhering to the “splendid first strike” believe that if the Soviets did provoke us we should then hit them with all our power and at “a time and place of our choosing.” This is “the massive retaliation theory as enunciated by … Dulles.”
Similarly, Bernard Brodie noted that Dulles’ doctrine “reflected a characteristically military dissatisfaction, one made familiar previously in the MacArthur hearings.” It represented nothing new about the defense of America or Europe but it was startling because it seemed to reject restraint symbolized by Korea for areas of not vital interests. In the event of a similar Korean incident, the Dulles’s doctrine implied much more than bombing the North Korean armies with thermonuclear weapons. We seem to be resolved to launch “a full-fledged strategic nuclear bombing attack on China!” And “we should probably have to include the Soviet Union as well.” The Dulles’s doctrine, Brodie concludes, “of course, is a preventive war, save that we have waited for an excuse, a provocation,” and hence of time not entirely of our choosing.
In theory, as the U.S.S.R. had no desire to provoke an all-out nuclear attack, the policy of massive response likely deterred any ambitions it would have had on Western Europe. Although the United States and NATO bloc would be hard-pressed in a conventional conflict with the Warsaw Pact forces if a conventional war were to occur, the massive response doctrine prevented the Soviets from advancing for fear that a nuclear attack would have been made upon the Soviet Union in response to a conventional attack.
It can be argued, however, that aside from raising tensions in an already strained relationship with the Soviet bloc, massive retaliation had few practical effects at that time. Before the development of the US nuclear triad, the threat of massive retaliation was hard to make credible, and was inflexible in response to foreign policy issues, as everyday challenges of foreign policy could not have been dealt with using a massive nuclear strike. In fact, the Soviet Union took many minor military actions that would have necessitated the use of nuclear weapons under a strict reading of the massive retaliation doctrine.
A massive retaliation doctrine, as with any nuclear strategy based on the principle of mutually assured destruction and as an extension the second-strike capability needed to form a retaliatory attack, encouraged the opponent to perform a massive counterforce first strike. This, if successful, would cripple the defending state's retaliatory capacity and render a massive retaliation strategy useless. Subsequent developments such as thermonuclear warhead miniaturization, accurate silo-based ICBMs, accurate submarine-launched ballistic missiles, stealth technology applied to cruise missiles, and GPS munitions guidance have resulted in a much more credible second-strike capability for some technologically advanced nations.
Still, if both sides of a conflict adopt the same stance of massive response, it may result in unlimited escalation (a "nuclear spasm"), each believing that the other will back down after the first round of retaliation. Both problems are not unique to massive retaliation, but to nuclear deterrence as a whole.
In 1957, three years after his announcement of massive retaliation, Dulles compromised his doctrine. In recent years, he wrote in Foreign Affaris, there has been no alternative to massive retaliation. But now the response can be confined to limited targets. Historian of the Cold War, Marc Trachtenberg, finds that since the very announcement, Dulles was moving toward the flexible response. Nevertheless, Eisenhower until the end of his term continued to dismiss out of hand the very idea of restraint in general war. In 1959, he said: “Once we become involved in a nuclear exchange with the Soviet Union, we could not stop until we had finished off the enemy.” There was no point to talking about “negotiating a settlement in the midst of the war,” no alternative, therefore, to hitting “the Russians as hard as we could.”
President John F. Kennedy abandoned the policy of massive retaliation during the Cuban Missile Crisis in favor of flexible response. The Soviet nuclear MRBMs in Cuba had very short flight time to their US targets and could have crippled the SAC bomber bases before the aircraft could take off and launch massive retaliation against the Soviet Union. Under the Kennedy Administration, the United States adopted a more flexible policy in an attempt to avert nuclear war if the Soviets did not cooperate with American demands. If the United States' only announced military reaction to any Soviet incursion (no matter how small) was a massive nuclear strike, and the U.S. didn't follow through, then the Soviets would assume that the United States would never attack. This would have made the Soviet Union far more bold in its military ventures against U.S. allies and would probably have resulted in a full-scale nuclear war. Thomas Shelling's deterrence theory discusses this more sharply: "signalling", or the use of threats internationally to deter an enemy from an attack or to make demands. If signals weren't being properly addressed by the Soviet Union, if the threats were not intimidating or coercing them to remove the missiles from Cuba, then the Soviet Union would simply not have believed that the U.S.'s policy of massive retaliation held any water. By having other, more flexible policies to deal with aggressive Soviet actions, the U.S. could opt out of a nuclear strike and take less damaging actions to rectify the problem without losing face in the international community.
Another reason for this was the development of a Soviet second strike capability, in the form of silo-based ICBMs and later SLBMs.