Massive Retaliation: A History of US Plans for Nuclear War

At the end of the Second World War, the United States possessed one complete atomic bomb ready for use and was making enough plutonium to potentially produce two more bombs per month. But, President Truman thought, there was no need for that number—no country, he thought, could withstand an attack by more than five or six atomic bombs without being forced to surrender. One year after Hiroshima, the entire US nuclear stockpile stood at 9 weapons, and by July 1947 this had grown to only 13 bombs and 34 specially-modified B-29 bombers to deliver them.

In 1949, however, the Soviet Union test-detonated its own atomic weapon (a virtual copy of the Nagasaki bomb). The US, in a panic, ordered increased production of its own nuclear weapons, and a crash program to develop bigger and better bombs and delivery systems, eventually culminating in the Intercontinental Ballistic Missile (ICBM) capable of delivering  hydrogen thermonuclear weapons halfway around the world with over one-million tons of explosive power. The next forty years would see a nuclear arms race on a massive scale, which drained treasuries, hobbled economies, and threatened the entire planet with instant nuclear annihilation.

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An iconic image of the Cold War–a Minuteman III nuclear missile in its silo.

At the beginning of the Cold War, US plans for a potential nuclear war against Russia were a simple continuation of the strategy that had won the Second World War against Japan: the US would launch continuous bomber attacks using nuclear weapons until the enemy’s cities were destroyed and surrender was offered.

In 1950, a strategic plan for nuclear warfare with the Soviet Union, called “OFF-TACKLE”, was prepared by the Strategic Air Command, a section of the US Air Force dedicated to the long-range delivery of nuclear weapons. The plan called for nuclear bombers stationed in the US to move within five days to bases in Britain and staging areas in Alaska or, if weather in Alaska was too severe, in SAC bases at Rapid City and Goose Bay, accompanied by six assembly teams to ready the bombs for delivery. There were 123 target cities in Russia, of which 60 would be hit in the opening days of the war and the remainder would be struck after reconnaissance flights. A total of 32 targets would be bombed in the first attack. It would then take about 30 days to destroy all 123 targets.

In 1950, neither the USSR nor the US had a ballistic missile capable of reaching the other’s territory.  It was assumed that bombers would be the primary delivery vehicle for nuclear weapons. By the end of 1955, however, a large amount of research had been done on the production of Intercontinental Ballistic Missiles (ICBMs) which could carry nuclear warheads over the North Pole between the US and USSR, and also on mounting a nuclear missile aboard a submarine, which could then approach Soviet shores undetected and reach targets deep inside the country. By 1957, both sides had workable long-range nuclear missiles.

In 1957 President Eisenhower gave “pre-authorization” to several military commanders, granting them the authority to use nuclear weapons on their own initiative, without any previous communication with the President, in the event of a major surprise attack on the United States. Eisenhower’s “pre-authorization” policy was designed to allow military commanders to launch a counter-strike on the Soviet Union if a surprise first-strike was able to knock out the President and other national commanders.  Significantly, however, it made no distinction between a Soviet nuclear attack and a major conventional attack – if the Soviet Union were to move into Germany with a large conventional military invasion, commanders in Europe were pre-authorized to use nuclear weapons against the invading troops.  For the rest of the Cold War, it remained US policy to initiate the first-use of tactical nuclear weapons to oppose any conventional Soviet invasion of Europe.

In 1958, a now-declassified memorandum reported on the results of a study carried out by analysts to determine what the effects would be of a hypothetical Soviet nuclear first-strike in 1961, and a full retaliation by the US.  According to the scenario, every Soviet city with a population greater than 25,000 people would be the target of a nuclear weapon; larger cities would receive more than one weapon. During the meeting, Eisenhower remarked that he remembered when the nuclear-warfare plan contained only 70 targets within the USSR, thought that the capacity to inflict that level of damage was enough for deterrence, and wondered whether we really needed the capacity for “100% pulverization”.

By mid-1959, the US nuclear arsenal had grown to such a level that it was becoming necessary to coordinate any retaliatory attack to reach the most effective targets.  Problems in nuclear planning appeared, as the Navy began deploying its own aircraft capable of delivering nuclear weapons, which sometimes conflicted with SAC planning. The introduction of the ICBM complicated the Air Force’s task, and the ballistic missile submarine gave the Navy a force of strategic nuclear weapons. Inter-service rivalry than kicked in, as both the Air Force and the Navy drew up their own strategic target lists, which often duplicated each other. As a result, the military recommended that a Single Integrated Operations Plan (SIOP) be produced, that would serve as the master plan for nuclear warfare.  Since it was assumed that worldwide communications networks would be knocked out early in any attack, the SIOP would allow nuclear weapons to be pre-sited and then launched against pre-planned targets as soon as the order came for counter-attack, without the need for continuous communication with the President.

In classified discussions concerning the SIOP, it was noted that some 2,400 locations in the Soviet Bloc were targeted. The discussion revolved around the options of either launching a pre-emptive first-strike against the USSR, or of a retaliatory strike against the Soviet Union after a Russian attack.  In the event of an American first-strike, the primary targets would be the Soviet ICBMs and bomber bases.  In 1959, however, the US had no spy satellite capability, and therefore could not be sure that an American first-strike would eliminate the Soviet nuclear capability.  In a retaliatory strike, on the other hand, there would be no point in hitting the empty Soviet nuclear bases, so the full weight of the American response would be targeted at urban areas and industrial targets.

In the end, the Pentagon settled on a mix of military and civilian targets. It was decided that a “cities-only” targeting strategy would not be sufficient, while a “military-targets-only” strategy would be unworkable since the US didn’t have reconnaissance capability to locate all the Russian ICBM sites.  Therefore, the plan settled on an “optimum mix” of both civilian and military targets. The Pentagon also estimated that perhaps as low as 15% of US manned bombers would survive to reach their targets, which gave added importance to ICBMs and led to new emphasis on the Polaris submarine-launched missile already in development.

The SIOP went into effect in 1960. It envisioned, in response to any attack on the US or Western Europe, a single massive series of attacks against targets throughout the Communist Bloc, including Russia, China and the East European nations, with the intent of destroying them completely as functional societies. It was assumed that 75% of the weapons would reach their targets.  Enough weapons would be sent to each target to give a 90% probability of moderate or severe damage.

By 1960, the inability of the US to directly verify the numbers of Soviet ICBMs led to fears of a “missile gap”, in which it was assumed that the USSR had a massive ICBM arsenal that could hit the United States.  While the Distant Early Warning (DEW) line of radar installations would give sufficient warning time of Soviet bombers, Soviet ICBMs would be on target within half an hour of launch.  It was therefore assumed that any Soviet attack would come in the form of ballistic missiles and not, as previously assumed, long-range bombers. This was a major change in nuclear warfare planning.

In 1961, the original SIOP was modified. The SIOP had been designed as a single and sudden attack that was pre-planned and designed to be carried out automatically once it was ordered into action; it was therefore rigidly fixed, and no part of it could be changed without affecting all the rest. It treated the entire Communist Bloc as one monolithic entity, which would all be struck at once, regardless of the situation under which the war was started.

By the end if his administration, President Eisenhower was beginning to become uncomfortable with the rigidity of the SIOP, and began exploring ways to make it more flexible. Under SIOP, for instance, the People’s Republic of China was to be attacked with nuclear weapons whether it had participated in an attack on the US or not—Eisenhower wanted to revise the plans to allow for the subtraction of particular countries like China. The new modified plan would be known as SIOP-62. About 3400 nuclear weapons would be used globally in the new SIOP, of which 1450 were to come from forces that were placed on alert to protect them from a Soviet initial strike. Each target was assigned multiple weapons to insure that at least one would give an accurate hit, and the highest-priority targets were assigned enough weapons to give a 97% probability of destruction. To increase the damage, each weapon was to be detonated at low altitude—which also increased the amount of radioactive fallout that would be produced.

By the time of the Berlin Crisis and the Cuban Missile Crisis, during the Kennedy Administration, the US was capable of launching its alert force of 1500 nuclear weapons in one hour, and could launch its entire nuclear force of 3400 weapons within 28 hours. American nuclear forces were to be directed at 3729 total targets. Since many of these targets were located together, there were 1077 “Desired Ground Zero’s” at which nuclear weapons were to be sent—480 of these were assigned to the alert forces. Every nation in the Sino-Soviet Bloc was to be targeted. A total of 295 “urban-industrial complexes” were targeted inside the USSR, and 199 of these were to be struck by the first wave of alert forces. It was expected that if the alert forces alone were able to strike, the attack would kill 37% of the entire population of the USSR and 55% of its urban residents, while an attack by the full American nuclear force would kill 54% of all Soviet citizens, including 71% of all urban dwellers—in the first 72 hours.

SIOP-62 was essentially an all-or-nothing plan—once set in motion, all the nuclear weapons would be used in one automatically-unfolding massive attack which would completely destroy the Soviet Union and China as functioning societies. The number of warheads that were actually launched was limited only by the amount of time available before a Soviet strike hit the US and destroyed our missiles and airbases. The alert force of one-third of SAC’s bombers, carrying half of the available nuclear bombs, would be sent immediately upon outset of war in the first wave to attack primary targets, with subsequent waves sent to lesser targets, or to re-hit targets from the first wave that had survived. The ICBMs would not be launched until after an attack had been confirmed. The US had 189 ballistic missiles available, of which 79 were Atlas ICBMs, 80 were the new Polaris submarine missiles, and 30 were intermediate-range Jupiter missiles based in Turkey and Italy. In both the US and the USSR, the vast majority of the potential strike force consisted of bombers. Each delivery vehicle (whether ICMB or bomber) was assigned a particular planned “time over target” to insure that the detonation of one nuclear weapon would not interfere with the trajectory of any others also assigned to that target. American planners expected a minimum of 16 million deaths in the US from a Soviet first strike. In the event of a US first strike, the Soviet retaliation would still kill as many as 3-7% of the US population.

There was no flexibility or alternate plans for smaller attacks on a limited set of targets, such as a limited strike solely on Soviet missile sites and avoiding Soviet cities. The lack of flexibility in the SIOP-62 led the Kennedy Administration to propose a new revised plan, to be known as SIOP-63.

The new SIOP-63 would be heavily dependent upon the Minuteman ICBM program which was then in development. The Minuteman was designed as a solid-fueled missile that could be launched within a short time, and was deployed in a specially-hardened underground “silo” for protection. A total of 590 “time urgent” Soviet targets were to be assigned to the missiles, to be struck during the first wave. Bombers would then be sent in to hit the lower-priority targets, and to place additional weapons on primary targets that had survived the first wave. The Minuteman was intended to move the US nuclear alert force away from bombers and towards missiles, which were more survivable in their silos than the bomber bases. The SIOP-63 also offered a number of options to withhold attacks against particular nations (a recognition of the political and military split between the USSR and Red China) or against particular classes of targets (such as cities).

By 1969, the US had a much larger number of ICBMs, some of which had Multiple Independently-targeted Re-entry Vehicles (MIRVs) which were multiple nuclear warheads that could each be directed to a different target, allowing a single missile to strike a number of different sites. The Soviet nuclear force had also changed during this time, from a predominantly bomber-based strategy to a rapidly-growing ICBM-based force which soon developed its own MIRV technology. The American ICBMs were based in hardened underground silos which allowed them to survive a first-strike and be available for retaliation; the Soviets focused on mobile ICBM launchers which would be difficult to hit in a fist strike (later the Russians also began to build underground missile silos). In addition, both sides had a sizable number of submarine-launched missiles which were also largely invulnerable to a first strike by the other side. And the bomber forces from both sides were increasingly vulnerable to newer and better air defense systems such as radar-guided anti-aircraft missiles. A new nuclear war plan, known as SIOP-4, was designed to deal with all of these changes.

The SIOP-4 had five different options for execution, ranging from a pre-emptive American “counter-force” first strike against only Soviet military targets located outside of the urban areas (the lowest-casualty option) to a full-out retaliatory attack on all targets. The counter-force first-strike option would use 1750 nuclear warheads (about 58% of the total nuclear force). The intent in all of the attack options was to prioritize the destruction of Soviet strategic nuclear capabilities, following that up if necessary with attacks on urban-industrial targets. Within each plan were options to attack one category of targets only, two categories, or all three: there were also a number of “withhold” options to spare particular types of targets or particular nations.

At this point, ICBMs made up the vast majority of US nuclear forces, with 1054 land-based ICBMs, 656 submarine-launched missiles carried by 41 Polaris subs, and only 300 strategic bombers. When the deployment of new ICBMs with MIRV warheads was complete in the early 70’s, the US expected to have about 5800 nuclear warheads on its missile force. The Soviets were expected to have available a force of 1500 ICBMs and a few hundred medium-range MRBMs—they were actively expanding their missile submarine fleet and were estimated to be about four years away from deploying their own MIRV weapons.

As the number of ICBMs and warheads grew on both sides, nuclear strategy began to change. In their hardened silos, mobile launchers and elusive submarines, the missiles were virtually invulnerable to enemy attack, and the earlier nuclear strategy embodied in SIOP, of targeting the other side’s strategic nuclear missile bases and airfields in the first waves, became obsolete. Now, each side was attempting to build its forces up to a level of both quantity and invulnerability that they would be able to absorb a first-strike by the other side and still have enough surviving “residual force” to destroy the other side in a retaliatory response—thereby deterring both sides from attacking the other. This doctrine became known as “Mutual Assured Destruction”, or MAD, and it dominated military thinking for the rest of the Cold War.

Planners for SIOP-4 concluded that both the US and the USSR had the capability to kill about 40% of the other’s population even after they had been hit by the other’s first-strike.

As new technologies such as MIRVs drove the numbers of nuclear weapons on both sides higher and higher, however, there were serious diplomatic efforts to begin a policy of detente, in which each side would act to defuse tensions and try to accommodate each other in a world of “peaceful coexistence”. Strategic Arms Limitation Talks (SALT) were begun with the goal of reducing the number of nuclear weapons through arms-control treaties. As Anti-Ballistic Missile (ABM) systems became more sophisticated and more expensive, it was realized by both sides that, while such systems could never be an effective defense against a first-strike of ICBMs, they may eventually be effective at stopping a much-reduced retaliatory second-strike. By therefore potentially preventing effective retaliation, these ABM systems were having a destabilizing effect on the nuclear arms race by provoking each side to produce ever-more warheads in an attempt to overwhelm the other’s defenses and maintain a lethal second-strike capability. Talks therefore began which would later lead to the ABM Treaty in which both sides agreed to avoid deploying any large-scale anti-ballistic missile defenses.

By 1972, both the Soviet and American arsenals were expanding rapidly, as newer more accurate ICBMs like Minuteman III and the Poseidon submarine-launched missile began to come into play. The SIOP by this time had approximately 4200 strategic nuclear weapons available. There were five major options for the SIOP, with three of these involving a pre-emptive attack by the United States (presumably in response to a Soviet invasion of Western Europe) and two involving a retaliatory attack by the US after a Soviet first strike. However, while the US could knock out many of the Soviet bomber bases and intermediate-range missile launchers in a first strike, it did not have the capability to knock out a significant portion of the Soviet ICBM forces, and was unable to prevent a devastating Soviet retaliatory response. And the opposite was also true—the Soviets could not knock out the American Minuteman missiles, and even just 100 surviving US ICBMs from a Soviet first strike would be able to wipe out 15% of the population of the USSR in retaliation.

The plan was designed with the intent to “moderately damage” at least 70% of the industrial capacity of the USSR and to kill at least 30% of its population. About 3200 nuclear weapons were aimed at Soviet ICBM forces and their command centers (“counter-force”), and about 700 were aimed at Soviet cities. The public policy of both sides was that they were not deliberately targeting civilian populations or cities, but that was a polite diplomatic fiction: everyone knew what “MAD” meant, and both sides knew full well that military targets were located in or near cities, and that attacks on “urban industrial targets” would mean the destruction of the city around them. Any large-scale attack by either side on any category of target could be expected to kill at least 100 million people. But the SIOP also contained contingency plans for the use of very small attacks during a crisis, even just a single missile or bomber strike. Such an attack could be on its way within 15 minutes of the decision.

During the Nixon Administration, nuclear strategy began to change subtly. The political aims sought by the US in its nuclear policies were to first prevent a war through deterrence, and second to attempt to limit any military conflict between the two superpowers as much as possible. But now a third goal began to be added: to guarantee that the US emerges as a more powerful force than its enemy in the post-war world, both by protecting American economic and political resources and by destroying those of the enemy. Rather than simply mutual destruction, the reasoning now went, maybe a nuclear war could be “won”.

Thus, although détente was still the diplomatic preference, the Nixon Administration simultaneously developed policies for successful nuclear war-fighting, spelling out a series of military options which carried the Kennedy-Johnson idea of “flexibility” to much higher levels. Nuclear attack plans were expanded to include not only an American first strike and a retaliatory strike after a Soviet attack, but also a series of “limited war” options intended to utilize nuclear weapons without setting off a full-scale war, and also a series of actions intended to ride out a full-scale nuclear exchange and still leave the option for further nuclear actions (termed a “trans-attack” strategy) to end the war on terms favorable to the US. Each of these broad plans was divided into a large number of target categories, with numerous options and withholds, which allowed some or all of them to be hit with the first attacks, not hit at all, or reserved to be hit later if escalation became necessary. Nuclear war was expected to be a series of steadily-escalating small steps, each one intended to dissuade the opponent from going any further. “High value targets” such as major cities or the civilian government leaders themselves, could be spared in the initial strikes and held in reserve as virtual hostages, to be destroyed later if escalation is not halted.

The strategic options spelled out by these new political policies were incorporated into a new nuclear war plan, SIOP-5, which was adopted in January 1976.

The Nixon Administration’s policy of flexible nuclear options that would allow the US to fight a nuclear war and attempt to maintain dominance in the post-war world was continued by the Carter Administration, even as the US sought diplomatic détente and continued negotiations with the Russians towards limiting nuclear weapons. The Soviets, meanwhile, made large and rapid investments in their nuclear forces, particularly ICBMs and intermediate-range IRBMs, through the 1970’s, and by 1980 had reached rough parity with the US in terms of strategic quantity, quality, and accuracy. In 1979 the US and USSR signed the SALT II treaty placing limits on the number and types of strategic weapons that each side could deploy, but later that year the Soviet Union invaded Afghanistan, international tensions rose, and the period of détente ended.

By this time, SIOP-5 had almost 40,000 potential targets for nuclear weapons, ranging from Soviet nuclear forces to command centers to urban industrial sites. The Carter doctrine was called “tailored counter-force”—it envisaged a series of carefully targeted selective attacks, each one escalating in severity, along with deliberate withholding of particular targets as “bargaining chips” to encourage the Soviets to negotiate and end the conflict.

To carry out this policy, the President Carter ordered the expansion of the US nuclear force capabilities, and began or expanded research programs that eventually led to many new strategic weapons systems, including the B-1 bomber, the “MX” ICBM missile, the nuclear cruise missile, the neutron bomb, and the highly-secret Stealth bomber, and also began programs to improve the survivability of US command and control to allow for changes in planning even while nuclear weapons were falling on the US.

These policies were highly controversial. Some military officials doubted the whole idea of attempting to wage a “limited” nuclear war in clearly defined stages—they argued that any initial use of nuclear weapons would quickly and unavoidably lead to an all-out exchange. In particular, there was heavy criticism of the added “launch-on-warning” option. Other military experts concluded that it was unlikely that the command and control system necessary to manage a limited-escalation strategy would survive the initial attacks, making the idea of a “protracted nuclear war” impossible. Public opinion, fueled by leaked versions of the directive appearing in the New York Times and Washington Post, saw the strategy as an attempt by the US to develop the ability to fight and win a nuclear war—a dangerous and provocative move that, aside from being impossible, would make the use of nuclear weapons more likely.

The Reagan Administration accepted and embraced the “war-fighting” strategy followed by the Nixon and Carter Administrations, but modified it further by increasing the emphasis on counter-force targets. By the mid-1980’s the United States either had or would have soon a number of new operational strategic delivery systems, such as the B-1 and B-2 bomber, Air-Launched Cruise Missile (ALCM) and Submarine-Launched Cruise Missile (SLCM), and the MX Peacekeeper ICBM, in large enough numbers and with high enough accuracy, to begin to think seriously about the possibility of a successful American first strike. The Peacekeeper ICBM, moreover, was originally designed to be a mobile system, in which a number of missiles would be randomly shuffled by rail cars between a large number of hardened shelters, to increase their survivability against Soviet missile strikes. (Because of budgetary limits, however, this plan was dropped and the Peacekeeper was deployed in the existing Minuteman silos.)

One important development at this time was advanced research work into Earth-Penetrating Warheads, which would allow a nuclear missile warhead or a bomber-dropped gravity bomb to burrow a distance underground before exploding, producing a much greater shock effect that would be capable of destroying even hardened targets like Soviet underground command bunkers and ICBM silos. For the first time in the Cold War, one side now had the realistic prospect of gaining the capability to launch a preemptive attack that would eliminate a significant portion of the opponent’s retaliatory capability.

The Soviets, whose ICBMs were not accurate enough for their own first-strike counter-force capability against the US, greatly feared this impending imbalance. Their fears increased further in 1983 when the US announced it would leave the ABM Treaty which had banned anti-missile defenses, and would attempt to develop a Strategic Defense Initiative, known popularly as “Star Wars”, to use satellite-based laser weapons to destroy enemy missiles on their way to the target. This, the Russians concluded with alarm, would end MAD and give the Americans overwhelming superiority—US earth-penetrating weapons would be able to destroy Soviet ICBMs in their silos, and the SDI system would be able to stop any retaliatory response by SLBMs or surviving ICBMs.

In 1989, the Soviet Union collapsed, the Cold War was over, and the 40-year nuclear arms race came to an abrupt end.

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