Fifty years prior to next Tuesday there were 95 to 100 nuclear warheads ready for Soviet forces to fire from Cuba. That date, Oct. 23, 1962, is the date on which the United States imposed a military blockade on the island, an effort to prevent Soviet ships from reaching the island with nuclear weapons. At the time, the US was unaware of the nukes already there, six to eight of which were married to SS-4 missiles capable of reaching 1,300 miles, with Washington D.C. and Cincinnati at the north and eastern limit of that range and New Orleans, Dallas, and Houston at the western edge. The rest of those (much smaller) warheads were meant to be used via cruise missiles against the US naval base at Guantanamo Bay, and against invading US ground forces.
That scenario makes up the first layer in the nuclear "order of battle" for the Cuban missile crisis. According to a paper out this month in the Bulletin of Atomic Scientists, this order is the "only way to calculate the likelihood of a full-scale nuclear war on October, 1962," and it's something that, until now, has gone largely unexamined in one of the most examined international crisis in history. "It was even more serious and dangerous than previous thought," the paper reads, though I'm at a loss for applying gradiations to the end-of-everything. Which is how most people I know interpret the seriousness of the Cuban missile crisis: that time when everyone everywhere almost died.
The order of battle is more or less the order of escalation available to the US and Soviet Union at the time, and how the whole shitshow could have progressed from the US blockading Cuba to the Soviet Union ignoring that blockade to the US invading to the launch of "local" nukes in the Caribbean and southeastern US to regional war in Europe to full-on torched skies end-of-everything global war. So, just in case you're taking the non-incinerated world around you a bit too much for granted, let's take a look at how exactly the Cuban missile crisis slides into World War III.
So, we already have the first layer, which is missiles launched from Cuba mostly at Cuba (infantry-stormed Cuban beaches anyhow). That nukes were on the island ready to use is the most ominous bit revealed in the new paper — aside from the sum total of all of the weapons involved globally — according to one of its two authors, Robert Morris. "The most astounding new information comes from a just published book by Sergo Mikoyan and Svetlana Savranskaya, The Soviet Cuban Missile Crisis," he writes in an email. "Look at the National Security Archive Website. The Soviets were not only planning to leave the tactical nuclear weapons in Cuba but transferring them to the Cubans!"
On the other side, the US had considered the use of nukes in an invasion of Cuba, but had decided against it. If the US invaded Cuba, and the Soviets responded with battlefield nukes, we would have almost certainly have graduated to the next level of conflict, in which the US responds with nuclear force against the actual USSR. That response would have come from Europe, where NATO and the US had roughly 4,375 nuclear weapons deployed, facing east. Most of those were battlefield nukes: artillery shells, land mines, surface-to-air missiles, short-range missiles. But, 450 of were married to ballistic missiles, bombs, and cruise missiles capable of reaching interior targets, like cities.
Meanwhile, the Soviet Union had around 550 ballistic missiles, aimed at European targets and US bases and allies in the Pacific. The respective nuclear forces of the two sides at this level were comparable, with the Soviet Union having a slight edge. Not that it would make much of a difference what edge the Soviets had in a regional nuclear conflict: the next stage, in which the Soviets were extremely edged out, is practically guaranteed once missiles are flying between Europe and the USSR. The Bulletin paper quotes John F. Kennedy's famous address on Oct. 22, the day before officially authorizing the blockade.
"It shall be the policy of this nation," JFK said, "to regard any nuclear missile launched from Cuba against any nation in the Western Hemisphere as an attack by the Soviet Union on the United States, requiring a full retaliatory response upon the Soviet Union."
Back in the Soviet Union, Nikita Khrushchev tells Kennedy the following, affirming from the other side that the situation is all or nothing: "The Soviet government considers that the violation of the freedom to use international waters and international air space is an act of aggression which pushes mankind toward the abyss of a world nuclear-missile war."
So, Rome is in ruins, London's cooked, and the scraps of Istanbul are wondering how they got mixed up in this. But it's still not quite global. The conflict is still technically a regional conflict, where, again, it would have no real reason to remain as the two quotes above make clear. At the global level, the US had 1,479 bombers, 182 ballistic missiles, 2,952 total nuclear weapons, and 1,003 refueling tankers. The Soviet Union had 42 ICBMs and 150 bombers; it later came out that the Soviet leadership viewed the US advantage as about 17-to-1.
On Oct. 28, the US and the Soviet Union made a deal ending the whole thing. The Soviets would pull their weapons out of Cuba, while the US would promise not to invade Cuba and also to remove its ICBMs from Turkey and Italy. Which it did but, by then, the US had already begun to deploy the first generation of Minuteman missiles capable of reaching from North Dakota wheat-fields to Soviet cities. So it was no big loss. And, at the same time, the Soviets had the Minuteman's analog, the SS-9, ready to fly in the other direction. In the most bizarre occurrence in human history, all of these things weren't immediately destroyed on Oct. 29.