World War II was the most destructive war in human history. Consider that, a conservative estimate of World War II fatalities is 60 million people, or roughly 3 percent of the world’s population at the time.

Yet, to an even greater extent than World War I, the outcome of World War II seemed to merely plant the seeds for another great power conflict. The battlelines were drawn when the Soviet Union created an Iron Curtain stretching across most of Central and Eastern Europe, while the United States led an alliance system throughout the western half of the continent.

For the next four and a half decades, military officers in the United States and the Soviet Union would create and tinker with plans to fight a NATO-Warsaw Pact war. For the United States, this meant seeking in vain to offset the Soviet Union’s numerical advantages without resorting to nuclear weapons early in a conflict.

Although successive U.S. administrations came into office vowing to reduce the role of nuclear weapons in America’s military doctrine, this proved impossible before the Reagan administration, when the revolution in precision-guided weaponry offered Washington a way to defeat the Soviet military juggernaut.

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Although the Soviet Union’s specific war plans, like America’s, remains classified, historians have been able to more or less ascertain how the Soviet army would have fought by using archives released by former Warsaw Pact member states like Poland and Czechoslovakia.

These reveal that, while Stalin was alive and through the 1950s, the Warsaw Pact maintained an almost entirely defensive posture aimed at protecting member states from a Western invasion. Likely reflecting America’s massive nuclear superiority at the time, these war plans did not envision the use of nuclear weapons in any capacity.

It was only after Stalin died, and specifically in the 1960s, that the Soviet Union designed new war plans. These were decidedly offensive nature and envisioned a blitzkrieg-type assault that allowed the Warsaw Pact to conquer most of Western Europe in a matter of days. It amazingly sought to integrate the liberal use of nuclear weapons with the Warsaw Pact’s formidable conventional military might.

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Specifically, the Soviet war planners (rightly) anticipated that the United States and its allies would resort to the massive use of nuclear weapons early in the conflict. As a result, they hoped to preempt their use in order to protect Soviet and Warsaw Pact territory.

Regardless, nuclear weapons were a central part of the Soviet Union’s strategy to conquer all of Western Europe. As War Is Boring has pointed out, on the Northern front alone, “Warsaw Pact plans called for 189 nuclear weapons: 177 missiles and 12 bombs ranging in yield from five kilotons—roughly a quarter the size of the bomb dropped on Hiroshima—to 500 kilotons.” Additional nuclear weapons would have been used in the Central and Southern fronts as well.

The larger nuclear weapons would be used to destroy major cities in Western Europe, including Hamburg, Bonn, Munich and Hannover in West Germany; Rotterdam, Utrecht and Amsterdam in the Netherlands; and Antwerp and Brussels in Belgium.

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No fewer than two nuclear weapons would have been used to destroy Copenhagen, and five nuclear weapons in total would have been unleashed on Denmark as well. A number of Italian cities would be targeted as well.

Even Austria, which was a neutral country in the Cold War, would not be spared from atomic destruction. Soviet war plans called for dropping two 500 kiloton nuclear weapons on Vienna.

Beyond trying to destroy major cities and population centers, the Soviet Union’s war plans called for making liberal use of tactical nuclear weapons against NATO military targets. Indeed, according to the Congressional Research Service, “ The Soviet Union deployed these [tactical nuclear] weapons at nearly 600 bases, with some located in Warsaw Pact nations in Eastern Europe, some in the non-Russian republics on the western and southern perimeter of the nation and throughout Russia.” At the time of the Soviet Union’s collapse, it is believed Moscow possessed some 20,000 tactical nukes, and it was likely higher than this in earlier years.

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Altogether, under one scenario contained in a joint Soviet-Hungarian planning document, the Warsaw Pact would unleash 7.5 megatons of nuclear weapons on Western targets in the opening days of a war.

This was not altogether different from the United States and its NATO allies. Indeed, the British Nuclear Deterrent Study Group concluded that Britain alone intended to drop around 40 nuclear bombs on the Soviet Union in the event of war.

The United States would greatly surpass that number, of course. America’s nuclear war plans are organized under the Single Integrated Operational Plan (SIOP), which was first created in 1960. Although the SIOP is a tightly guarded secret, some information on the earliest SIOPs has been declassified. These show that, early on in the Cold War, “A full nuclear SIOP strike launched on a preemptive basis would have delivered over 3,200 nuclear weapons to 1,060 targets in the Soviet Union, China, and allied countries in Asia and Europe.” Under the plan, the United States would not distinguish between Communist nations that were at war with the United States and ones that were not (sorry, China).

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What made the Soviet Union’s warfighting doctrine so different from NATO’s is that Moscow believed nuclear weapons would only be one part of the fighting, and not even necessarily the decisive factor. For the United States and its allies, the use of massive amounts of nuclear weapons was more or less the extent of the fighting, given the extensive destruction it would cause.

By contrast, the documents released by the former Warsaw states reveal that the Soviet Union believed that nuclear weapons would be used to shape the overall battlefield. The traditional metrics of warfighting—namely, defeating the enemy’s forces and occupying his territory— would determine the outcome of the war.

As one Czech scholar, Petr Lunak, explains, “Contrary to the U.S. doctrine of massive retaliation, the Soviet bloc's response would have made use not only of nuclear weapons, but, in view of Soviet conventional superiority, also of conventional weapons. This massive retaliation, in the Soviet view, did not make planning beyond it irrelevant. Contrary to Western planners of the time, Soviet strategists assumed that their massive strike would only create the conditions for winning the war by the classic method of seizing enemy territory.”

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He further elaborates: “In the thinking of the Czechoslovak and probably of the Soviet military headquarters of the time, nuclear weapons would determine the speed of war but not its entire character. Since nuclear arms considerably shortened the stages of war, according to the Eastern logic, it became necessary to try to gain the decisive initiative with a powerful strike against enemy forces, making use of the moment of surprise.”

Thus, along with the liberal use of nuclear weapons, the Soviet Union and its Warsaw allies planned to launch a massive blitzkrieg aimed at taking over most of Western Europe. The goal was to break through NATO’s frontlines, and “advance swiftly into the depth of his defense and move into operational space.” In order to achieve these rapid initial successes, the Soviet Union aimed to achieve a troop advantage of 5:1 or 6:1 along the main points of attack.

The objectives of the campaigns differed depending on the front. For example, after the nuclear exchange, the Czechoslovak Army was supposed to pierce through NATO frontlines and quickly seize Nuremberg, Stuttgart and Munich, all of which were part of West Germany at the time. By the ninth day of the conflict the Czechoslovak Army, perhaps with some Soviet backing, was supposed to conquer Lyons in southern France. After that, Soviet reinforcements would push on to Pyrenees, the mountain ranges that form the border between Spain and France.

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Simultaneously with these operations, Polish and Soviet troops were supposed to conquer most of the northern portion of the continent. Specifically, they intended to invade West Germany, Denmark, The Netherlands and Belgium. Securing these areas was crucial in order to prevent the United States, Canada and Great Britain from landing reinforcements for NATO on the northern part of the continent. As such, they hoped to have secured Denmark within a week and reach the Atlantic coast within 14 days of the start of the fighting.

This plan was obviously highly ambitious, and many military observers strongly doubt that the Warsaw Pact militaries even had the necessary motorized vehicles to pull off such a quick invasion throughout much of the Cold War.