As late as 1987, two years before the Berlin Wall fell, the United States seriously considered the possibility that the Soviet Union might start World War III.
This Defense Department map shows the broad outline of a two-pronged Soviet attack on Western Europe. Planners expected one army to march across the Northern European Plain into the Low Countries and another to dive across Bavaria into France and the Iberian Peninsula.
At the time, the Soviets had thirty forward-deployed divisions in Eastern European to spearhead an invasion force with another 94 in Western Russia. NATO was outnumbered and counted on the threat of massive nuclear retaliation to deter the Reds.
Atomic weapons played a different role in Warsaw Pact planning. Far from a last resort, they were envisaged as something like big artillery pieces that could clear the way for a ground invasion.
In the event of a Soviet invasion, the Americans expected secondary attacks on Scandinavia and Southwestern Europe.
In the north, the goal would be to cut off neutral Finland from Norway and Sweden and then move Soviet forces down the coast toward Oslo and Stockholm. Only Norway was a member of NATO, but it would have been impractical for the Russians to respect pro-Western Sweden’s neutrality.
In the south, neutral Austria and communist Yugoslavia would similarly be treated as enemies in order to cut off Turkey from the fighting in Central Europe and force the Allies to retreat into France.
Of the two, the Balkan offensive would have been the most crucial. Without it, a Soviet army making its way across southern Germany risked being encircled in case the Allies managed to push back the northern invading force.
Polish invasion of the Low Countries
Polish troops were meant to take the lead in occupying the Low Countries.
War is Boring writes that among the Warsaw Pact armies, Poland’s was second in size only to the Soviet Union’s:
It had a peacetime strength of 361,000 troops and could expand to 865,000 upon mobilization. It had fifteen combat divisions, versus the US Army’s ten divisions today. The Poles had 2,880 tanks, 2,750 armored personnel carriers and more than 2,000 artillery pieces.
Yet despite this superiority in numbers, the Poles still planned to use dozens of nuclear weapons.
The above 1970s map calls for nuclear strikes on virtually all of Northwestern Europe’s major cities, including Amsterdam, Antwerp, Brussels, Hamburg and Hanover.
Even tiny Denmark, with a population of just under five million at the time, would have been hit with no fewer than five nuclear weapons, including two dropped on the capital city of Copenhagen.
The casualties would have been enormous.
Petr Lunak, an historian, called the whole plan a “fairy tale”, telling The Telegraph newspaper:
They really planned to send ground troops out in the field and have them fight for a few days until they died from radiation.
Seven days to the Rhine
A more modest proposal was declassified by the Polish government in 2005 and is known as “Seven Days to the River Rhine”. It also called for nuclear strikes on cities in West Germany and the Netherlands but spared nuclear-armed France and the United Kingdom in hopes they might be persuaded to sit out the war.
Under the plan, Hungarian forces were meant to capture what was left of Vienna while Czechoslovak troops would be send into post-atomic Munich, Nuremberg and Stuttgart.
The offensive would halt at the Rhine, similar to the plan presented by the fictional General Orlov in the 1983 James Bond film Octopussy.
Conquering France in a week
After securing Bavaria, the Czechoslovak army was supposed to conquer Lyon in the south of France. After that — presumably having lost quite a few soldiers to radiation poisoning — Soviet reinforcements would have arrived from the Carpathian Military District to push all the way down the Pyrenees.
The idea was to accomplish this within a week, which seems ambitious.
War is Boring again:
The famous German blitzkrieg through France in May 1940 astounded the world by advancing 35 miles per day. […]
To meet their deadline, the East Bloc armies would have needed to double this rate of advance to some seventy miles per day, all while fighting well-trained defenders armed with advanced weapons.
The difference with 1940, of course, being that this war would be nuclear. To meet their schedule, the Reds planned to atom-bomb their way through France.
But they would have faced the same problem as the Poles: how to reinforce and resupply their troops through an atomic wasteland.
Why were the Soviets so keen on nukes?
Zachary Keck reported for The National Interest in 2015 that the Warsaw Pact maintained an almost entirely defensive posture through the 1950s:
Likely reflecting America’s massive nuclear superiority at the time, these war plans did not envision the use of nuclear weapons in any capacity.
That changed in the 1960s, when the two superpowers approximated parity and the offensive use of nuclear weapons was first envisaged.
This distinguished Soviet from NATO planning. The Western alliance never planned for a partly-nuclear conflict. From its point of view, World War III would be fought with either conventional or nuclear weapons. A combination was considered infeasible.
Soviet thinking shifted again in the 1980s, when the United States embraced a new doctrine called AirLand Battle and started developing advanced weapons systems like lasers and stealth.
William E. Odom, the director of the National Security Agency under Ronald Reagan, wrote in retirement that the Soviet general staff now faced the prospect of a series of NATO deep attacks that could unhinge Soviet offensive operations:
It was beginning to make tactical nuclear weapons appear much less attractive to Soviet planners, but […] Soviet industry could not provide this new generation of higher technology weaponry being fielded by NATO.
Which is one of the reasons the Cold War ended that decade.