There are a number of episodes in the Cold War history that testify to the dangers of nuclear weapons. There were quite a few close calls and some of these were (much) closer than others. One of them, which is often described as being one of the closest calls, is the September 1983 false alarm, also known as the Stanislav Petrov incident. In brief, the popular version of the story is that the Soviet early-warning satellites generated an alarm, which Petrov recognized as false thereby averting a truly catastrophic full-scale nuclear war.

With time, these episodes generate their own narratives, which give us a convenient way of thinking about the events of the past. Besides, who doesn't like a good story about avoiding an apocalypse? The problem, of course, is that these narratives may not be quite correct. But then, what is "correct"? I am sure historians deal with these kinds of things all the time, and the profession has a way of thinking about these issues. I am not a historian, so I don't know what to do in these cases. Neither I pretend to know what actually happened (does anyone?). But I can offer bits of evidence and my thoughts hoping that they could contribute to a narrative that is in some sense "more correct."

The best description of the incident is in David Hoffman's book "The Dead Hand," which I highly recommend. (Full disclosure - I helped David with preparing some materials he used in the book, the Kataev archive among them, and we discussed many things, including the Petrov episode.) Hoffman interviewed Petrov and used other materials to reconstruct the events of that day. I must say right away that there is absolutely no reason to doubt Petrov's account of the events. Also, there is no doubt that Stanislav Petrov did the right thing when he reported up the chain of command that in his assessment the alarm was false. That was a good call in stressful circumstances and Petrov fully deserves the praise for making it.

But did he literally avert a nuclear war and saved the world? In my view, that was not quite what happened. (I would note that as far as I know Petrov himself never claimed that he did.)

To begin with, one assumption that is absolutely critical for the "saved the world" version of the events is that the Soviet Union maintained the so-called launch-on-warning posture. This would mean that it was prepared to launch its missiles as soon as its early-warning system detects a missile attack. This is how US system works and, as it usually happens, most people automatically assume that everybody does the same. Or at least tries to. This assumption is, of course, wrong. The Soviet Union structured its strategic forces to absorb a nuclear attack and focused on assuring retaliation - the posture known as "deep second strike" ("ответный удар"). The idea was that some missiles (and submarines) will survive an attack and will be launched in retaliation once it is over.

The full story is a bit complicated - the Soviet Union did invest in early-warning radars and satellites in the 1970s. That development, however, did not mean that the Soviet Union had a chance of implementing launch on warning even if it wanted to. Its geographical position made it very much impossible, with or without dual phenomenology (i.e. satellites plus radars). The early-warning system did play a role in the decision-making mechanism, but that role was to trigger the release of a preliminary command that would bring the strategic forces into the state from which a retaliatory strike is possible. Check this excerpt from the Russian Strategic Nuclear Forces book for a more detailed description of the procedure.

In the 1980s the Soviet Union began implementing measures to support the "launch under attack" option ("ответно-встречный удар"). This strategy was intended to take advantage of the fact that even a well-coordinated strike against strategic forces could not hit all targets at the same time. This meant that while some missiles will have a chance to escape from under attack even though others are already destroyed. The move toward the launch under attack required substantial investment, but in the 1980s the Soviet Union was on the way there.

What is important here is that in either case the Soviet Union would have waited for actual nuclear detonations on its soil. Nobody would have launched anything based on an alarm generated by the early-warning system, let alone by only one of its segments - the satellites.

In any event, an operator of the space segment of the early-warning system is not the person who determines the course of actions. Once the computer classifies the signal as an indicator of a launch, it generates an alarm that is automatically sent up the chain of command (especially if it is not a single launch). There were at least three assessment and decision-making layers above the command center of the army that operated the satellites - command centers of the early-warning army, the Air Defense Forces (which was a separate service back then), and, finally, the General Staff. The decision to act would have been taken only at the very top. It is certain that the alarm would have been recognized as false at some stages. But even if it wasn't, the most radical thing the General Staff (with the involvement of the political leadership) would do was to issue a preliminary command. No missiles would be launched unless the system detected actual nuclear detonations on the Soviet territory.

Having said that, what Stanislav Petrov did was indeed commendable. The algorithm that generated the alarm got it wrong. The designers of the early-warning satellites took particular pride in the fact that the assessment is done by computers rather than by humans. So, it definitely took courage to make that call to the command center up the chain of command and insist that the alarm is false. We simply don't know what would have happened if he kept silence or confirmed the alarm as positive. And, importantly, he did not know it either. He just did all he could to prevent the worst from happening.

P.S. False alarms, of course, happened all the time. This one seems to have been more serious than others. It is mentioned in a some semi-official accounts, like this one "Рубежи обороны - в космосе и на земле" (p. 152). That account placed the episode in July 1983, but that may be an error. The episode resulted in a "stern conversation" between the minister of defense and the chief designer of the system. Other incidents are mentioned briefly as well - apparently the Soviet Union had its own "training tape" accident in the 1970s.