The False Alarm That Nearly Sparked Nuclear War

The date was September 26, 1983. A lieutenant colonel in the Soviet Air Defence Forces sat at his command station in Serpukhov-15 as sirens blared, indicating nuclear missiles had been launched from the United States. As you may have surmised by the fact you’re reading this in 2021, no missiles were fired by either side in the Cold War that day. Credit for this goes to Stanislav Petrov, who made the judgement call that the reports were a false alarm, preventing an all-out nuclear war between the two world powers. Today, we’ll look at what caused the false alarm, and why Petrov was able to correctly surmise that what he was seeing was an illusion.

Detecting Missiles By Infrared

Stanislav Petrov pictured at his home in 2016.

Petrov was in charge of monitoring the Oko early warning satellite network, which consisted of a series of satellites in highly elliptical Molniya orbits. This orbit was cleverly chosen by Soviet scientists to allow the Oko satellites to have a grazing view of the continental United States, which presented the biggest threat of intercontinental ballistic missile (ICBM) attack at the time. By glancing across the Earth’s edge with their infrared sensors, rather than gazing down upon it, the infrared energy from hot missile exhaust could easily be spotted against the cold background of space, rather than the Earth’s surface. The aim was to cut down on false positives from phenomena such as wildfires and oil rig burnoffs, while also providing good coverage without requiring a large number of satellites.

On that fateful night in September, however, the unique orbit of the Soviet satellite was to cause a major problem. The Oko system raised an alarm shortly after midnight, indicating that a single missile had been launched from the United States. As the sirens were going off around him, Petrov almost froze. The political climate at the time was fraught, with all-out nuclear war a constant threat.

The siren howled, but I just sat there for a few seconds, staring at the big, back-lit, red screen with the word ‘launch’ on it.

The initial alarm was followed by further alerts, showing five missiles in total. Despite the indications that all hell was about to break loose, Petrov didn’t immediately pass the alert up the chain of command.

Is This Thing Broken?

With only minutes to react to a strike, time was of the essence, but things didn’t add up. Starting a nuclear war with just five missiles didn’t strike Petrov as a believable strategy, and satellite radar operators were unable to report detecting any launches. The Oko satellites were also new and relatively untested thus far. Thus, rather than report that a nuclear strike on the USSR was underway, Petrov elected to go with his hunch and report that the system was malfunctioning.

Twenty-three minutes later I realised that nothing had happened. If there had been a real strike, then I would already know about it. It was such a relief.

A diagram indicating the rough relative positions of the sun, the Oko satellite, and and the US missile field it was tasked with monitoring.

Petrov’s gut feeling turned out to be on the money, and the dogs of war were kept on a leash that evening. It was indeed a false alarm, rather than American missiles, that had caused the warning. The date of the incident happened to be right around the autumn equinox. Due to the position of the sun and some high-altitude clouds, sunlight was reflected onto the satellite’s infrared sensors, triggering the satellite to report multiple missile launches. The incident led to the Soviet Union creating a complementary geostationary satellite system in order to corroborate any indications of missile launches from the USA.

Stanislav Petrov was never rewarded, or particularly admonished for his decision. Eventually, he was demoted on a technicality for not filling out his diary while tangling with the agonising decision as to whether the Earth should burn in nuclear fire on that cold September night. He lived out the rest of his life in Russia, passing away at the age of 77 in 2017.

Disaster was thus averted by Petrov’s actions; in the hair-trigger military environment of the time, it’s likely that USSR officials warned of incoming US missiles likely would have given the order to launch, causing untold devastation. Instead, we’re left with a great story and an even more poignant lesson. Redundancy is always key in systems that deal with matters of life or death, and it’s even more polite to ensure that when said lives (or deaths) can be measured in the millions or billions. That, and that sometimes you’ve got to err on the side of caution, particularly when nuclear war is involved.

54 thoughts on “The False Alarm That Nearly Sparked Nuclear War

  1. “we’re left with a great story”

    Decades later it still gives me watery bowels thinking about it. I am very much against going back to the good old days of mutually assured destruction, but it looks like we’re heading that way with either Russia or China or both at the same time.

    1. Since my more detailed reply apparently contained some hot words & isn’t appearing, the short answer to your worries is no, there will be no war between the superpowers. EVER.

      China doesn’t want war (US owes them billions and that was why the previous president was so anti China, but China is very much ‘pro America’ & very much wants the rest of the world to help them deal with their insane economic growth) and Russia at worst just wants to annex the UK (heh) wich obviously wont happen either.

      Bottom line both those superpowers just want to make money, not war, you can sleep safely at night.

      1. There’s quite a few assumptions in there that are thoroughly unproven, and I would argue that most of them are disproven at this point. First, I would contend that China is decidedly not ‘pro-American’. Chinese and American foreign policy do not align in several key areas (i.e. Taiwan, Hong Kong, Belt and Road, Industrial espionage, cyber terrorism, etc.) In fact, it would be easier to simply identify the very few areas where they do align, but I’m struggling to find an example. Economically, there is significant trade between the two with China holding an enormous trade deficit over the US, but here again the sides do not see eye to eye.

        The most pernicious fallacy however is that the debts that China holds are somehow a deterent to conflict. I can’t object enough to this line of reasoning. That debt is little more than a rounding error when compared to the cost of waging a modern industrial conflict. If the relationship deteriorated enough to lead to conflict, that wouldn’t even cause China to think twice. China would pay many times the value of that debt for a mythical stealth weapon that accomplished half as much infrastructure damage as the accumulation of that debt by the US did. (That’s ultimately on the US though.)

      2. China wants Taiwan, the US doesn’t want China to have TSMC.

        At some point China will either blockade Taiwan to force the issue and/or the US will enter into a formal defence pact with Taiwan to save them.

        What happens next?

    2. One difference is that almost every US Navy ship now has anti-ballistic missile missiles. In fact, the Standard Missiles that are doing anti-aircraft duty can even take out satellites in LEO.

      It isn’t clear that something like “mutually assured destruction” exists with China.

      As for “both at the same time,” Russia won’t even license their good fighter jets for production in China, they’re not actually very close of allies.

  2. September 1983 seemed like a familiar date. On 1 September 1983 the Soviets shot down Korean Air Lines 007, killing all 269 people aboard. To say tensions were high at this time would be putting it mildly.

  3. July 7, 1983 Samantha Smith of Maine flew to Moscow to talk about peace.

    When we walked Montreal to NYC started on April 3rd 1982, there was a teenager who walked some of the way.

  4. When I read the beginning of the article and read they used a highly elliptical orbit to get that side on view my immediate thought was why not put it in geostationary orbit at the right position to always have the best side view. Good thing I finished reading, though the fact that it seems to have only occured to them after the incident doesn’t say much for soviet forward thinking.

    1. 1983. Designed maybe in the mid to late 70s. Vidicon tubes. Maybe megapixel imagers. Maybe mirror scanners. 1200 baud modems. Image resolution from 22,000 miles is not nearly as good as from a couple hundred miles. I don’t know what they had for relay satellites in that era but geosync over North America is on the other side of the world. No direct view for communication. Would need to be a ground station somewhere with a view and/or a relay. Complicated logistics. They had pretty sound reasons for doing it this way. Not what you’d do today but you need to consider the whole system. I don’t agree with politics but their engineering generally isn’t bad when you consider everything.

      1. “1200 baud modems.” In the 1960s, the U.S. military had high speed datalinks that were remotely flying F-106 fighters to intercept unknowns, and megabit tropospheric scatter communications. You have to realize that military budgets were higher than typical household budgets, and military systems did not typically use consumer-grade technology.

    2. You’ve made some excellent deduction about a Russian multi million sattellite program based on just a few lines of text in a hackaday article. I could not have done better.

  5. There they go, one-upping us yet again. In 1960, the U.S. had a similar false alarm that identified the moon as a large number of submarine-launched ballistic missiles.

      1. I am aware of that. That’s why I specified “the U.S.” in the next sentence. I think that most readers can pick this sort of thing up from context.

        I’ll go on, now that I’m writing.

        Back in the early 80s, I worked for the U.S. Air Force as an Aircraft Control and Warning RADAR technician. That’s a unit of the Department of Defense of the United States of America, to be clear. I had heard the stories about the false alarm that caused fighter jets to be launched against the moon, and I also noticed that the system I worked on, an AN/FPS-26A height finder RADAR system, which was designed and built AFTER said incident, had a vertical sweep rate of 19 cycles per minute, while earlier systems I had worked on all had 20 cycles per minute sweep rates. I was curious about whether this change in sweep rate could possibly be related to the false alarm incident.

        So I did some calculations in two different areas:
        1) Using the ITT Radio Engineer’s Handbook, which included a very involved formula for determining what the maximum range for RADAR detection would be, based on many factors, including transmitter power, frequency, and pulse width, receiver bandwidth and sensitivity, distance, antenna horizontal and vertical angular beam widths, target cross-sectional area and reflectivity, and several other factors I’ve since forgotten but was able to either measure or make educated guesses about, I calculated the margin the system would have for detecting the moon.
        2) I calculated the distance to the moon in RADAR seconds.

        The first calculation showed that there was a very good chance that our 2 MW, 4.5 us pulse could be detected, even with a half-million mile round trip, and the second showed that with the a 20 cycle/minute antenna scan, it WAS possible that a transmitted pulse aimed directly at the moon while the antenna was scanning would return almost exactly as the antenna was pointed the same direction again on a subsequent scan. This varied according to where the moon was in its orbit, but yes, it was certainly possible for a 20 scan/minute height finder system to spuriously detect the moon. And furthermore, this type of false alarm was not possible for an antenna scanning at 19 scans/minute, because the antenna would be pointing to a different elevation when the pulse returned.

        Armed with these facts and vibrating with youthful exuberance, I calculated where the position of the moon would be a couple of hours before moonset (we only had a limited elevation scanning range), and popped down to the operations room, happy to see that nothing was going on, and the ops officer had no objection to my taking over the system for a quick unscheduled “performance check”, on the understanding that it would be returned to service at a moment’s notice if required.

        But how to get around the 19 scans/minute problem? Easy. Our antenna had a hydraulic positioning system, which allowed us to set the center elevation and scan amplitude, so I set the amplitude to zero, and adjusted both the azimuth and elevation manual controls to where I had calculated the moon to be.

        It took me a couple of minutes of blundering my way across the sky with the controls, but when I hit it, there was no mistaking what I saw. It was amazing. Keep in mind that the moon is a sphere of considerable radius, which means that different points on it would appear to be at different distances. Also consider that a great deal of the moon’s surface is covered with concave surfaces we call craters. What I saw on my range-height indicator was a very large number of targets at all ranges, all coming from the same direction. Yeah, I can see how a computer would have shat its digital pants on seeing that kind of display. In our situation, the RADAR data did not get automatically processed, though – all target measurements were taken by human operators, and the one on duty at the time knew what I was doing, so we didn’t actually scramble any fighters to intercept the moon that day.

  6. The question with this kind of warfare is, do you want to see your own children burn first, or “theirs”.

    It is sick.

    I was 8 years old that day. Unaware as most are, at that time, that age, I think.

    Remove these looming horrors, it brings us all nothing, nothing at all, only death.

    If you say “yeah but”, and then some argument, no, it is sick.

    1. It is sick. And there are, and always will be sick people in the world. The technology exists and until it is used to destroy itself, always will. Unfortunately, if the “nice” people rid themselves of the technology, there won’t be anyone to defend against the “not nice” people.


  7. In the early 70s i was very scared by no known “Siren Tests” at the age of 5 or 6.
    I ran in the empty house, turned on radio and television but no emergency call was made.
    A neighbour and ww2 veterean laught at me later …

    1. Where I lived, they did air raid siren tests at noon, on about a monthly basis. I remember thinking that if the Soviets wanted to attack us, all they had to do was attack at noon, because everybody would assume it was just a test.

  8. This story is mostly hype and speculation, the system worked as it had multiple layers, if you want to talk about reality tell us about systems that failed and why they did. Actual lessons learned, hacks that would have improved safety and reliability, or ones that were used to keep something working when it ‘s design or manufacturing failed. Can you even see the difference?

      1. Why is it “negative” to be skeptical that all the other people on the Other Side were mindless, murderous robots who would have burned the whole planet from a single sensor reading?

        It seems the story itself tries to be positive, but contains a lot of negativity. Perhaps pointing that out is “positive.”

  9. Re Petrovf, a counterpoint I hadn’t considered, from Thierry Etienne Joseph Rotty on Quora:
    “The idiot should have been taken out the back and shot.

    The procedures in place were very simple: if and when an infra-red sensor detects a heat source, LIeutenant-Colonel Petrov had to call the next echelon and inform this of this simple fact.

    The next echelon would then run a systems verification check to see whether there might be a malfunction in the satellite in question.

    In this case, it would have allowed the system analysts to determine quickly that the heat source was relatively static (in space, everything is in motion), in this case, the Sun, rather than a moving object such as a missile.

    This is a very simple procedure that is identical in the US and Russia (previously the Soviet Union).

    By not reporting the alert, Petrov effectively made it impossible for the technicians to run a systems malfunction check. It took the specialist two weeks to figure out what had happened, something that could have been solved in literally under two minutes if the idiot had made the phone call.”

    1. The Sun is moving, but that is not the point, the Earth is rotating and the satellites are orbiting, so the systems malfunction check might not have detected the IR “signatures” because of the clouds rotating out of the field of view. So, if they weren’t detected during the system test, does that mean it was a false detection, or a real one?

    2. Thierry is an idiot. Had Petroff passed that up the chain immediately, his superior that was just contemplating the meaning of life would say “Well, that’s it I guess” and pass that along to the nearest political comrade and Thierry would be in a cave freezing and thinking how his come his life turned to crap so fast. And he wouldn’t be writing stupid shit on Quora.

      1. Which is especially chilling, when you consider that MANY members of the military would never question the regulations, and do exactly as they had been trained. The USAF once did some reliability studies, in which they disabled ICBM launchers and simulated attack scenarios without telling the launch officers that it was an exercise. The Air Force was alarmed that fully half of the launch crews failed to launch when they believed it was a real-world event. _I_ was alarmed that nearly half of them DID execute the full procedure, even when they truly believed it was for real. I was further shocked that they would even do such a test. History if full of “but the gun wasn’t even loaded” incidents.

        1. I consider that an unrelated scenario. Within the detection, command, and execution chain, the launch officer has no external inputs other than to see to her/his mission, analogous to a tank loader wondering, “hmm, does my gunner know what the hell he’s doing?” I can understand that not everyone is cut out to execute a nuclear strike. I’m glad that half of the crews followed through. I think it’s absolutely valid to realistically test the crews… provided the testers were SURE they had disabled the ability to launch. If none of the crews had tried to execute, that’s something the policy makers should know about.

          1. I think you may not fully understand the nuclear deterrent. The object is NOT to obliterate your opponent if he attacks you. The object is to convince your opponent that attacking you would be suicidal, so that he WON’T attack you. Since the Soviets were just as scared of us as we were of them, it was not difficult to convince them of that. We just had to show that it was technically possible, and they already believed we were bloodthirsty enough to actually go through with it. But the fact that human beings are capable of taking actions that will directly kill hundreds of thousands of people is still shocking.

            I guess that’s why we have armies. Armies can train people to behave in ways that are contrary to their nature, and let nations project power while assigning the resulting guilt to a few of their citizens. We really don’t care that two missile launch officers will probably kill themselves over the guilt, because this can absolve the rest of us of the guilt over those thousands of murders. Of course, not all of them will kill themselves, but few of them will continue as functioning human beings, so they can still be considered casualties. It’s a huge win, where the enemy loses a hundred thousand, and we lose two.

            It’s not easy. One historian claimed, after interviewing a large number of soldiers after World War II, that fewer than 15% of them ever fired their rifles. The number in Vietnam may have been even smaller, since most of those soldiers there were there against their will. But again, militaries studied this phenomenon, and have in recent years learned how to train soldiers to shoot without thinking, just responding to threats with nearly reflexive actions. Add to this the “video game” perception that drone operators and bomber crews have, and the result is higher effectiveness ratings for warriors, who can then discarded because there is just no fixing what this does to a human being.

            Before you react, I was a “video game warrior” myself, maintaining the perimeter defense of the U.S.A. for six years. I looked at blips on a ‘scope that represented inbound Tu-95 and Tu-16 bombers, and then F-4 and F-106 interceptors, outbound. Every time, the game played out the same way, with the bombers turning around, and the interceptors returning to base. I am forever grateful that I never had to participate in a hot battle, that the game never ended with blips disappearing from the ‘scope as aircraft were shot down. This was just dumb luck, as I hadn’t even considered the consequences of that when I enlisted. Sure, I thought about how I could be killed, but never about how I might have to kill.

          2. To address your other point, though, “provided the testers were SURE they had disabled the ability to launch”, I will cite two incidents:
            1) Chernobyl, 1986. The accident and subsequent meltdown occurred during a TEST, in which the operators were confidant that they could shut down the reactor safely at any point.
            2) Seattle, 1989. The Evergreen Point floating bridge was undergoing a test on its drawbridge section, during which the motors were disconnected so that the bridge could not actually rise, thereby allowing the test to be done without shutting down the highway. But rise it did, and a car slammed into the concrete bridge span. This sort of accident appears to be fairly common for drawbridges. In all cases, the operators are absolutely SURE that the bridge cannot open.

  10. Why?

    After mulling over it for half-a-life I’m pretty sure it is sheer luck.

    And oh, BTW: Stanislav Petrov should at least have a couple of streets named after him.

    Regardless of whether one may agree with his ideologies or not, many a street possibly owes its very existence to this guy’s cold blood.

  11. We came even closer during the Cuban Missile Crisis. Unknown to the US, the Soviets already had in place in Cuba tactical nuclear weapons for use against any invasion and those were under local Soviet control. Had the US invaded as many in the US military had wanted, they would have been used as claimed by those in charge there writing after the fall of the Soviet Union.

    Also, when a Soviet sub reached the US Navy’s blockade line around Cuba [called a “quarantine” to avoid the act of war connotations of a “blockade”] a certain number of hand grenades were dropped into the water as the international signal for the sub to surface. That sub crew did not know that and thought it was under depth charge attack. They had a nuclear torpedo and were authorized to use it if three designated individuals onboard voted to approve that. Two voted yes, one no.

    The Man Who Saved the World [Vasili Arkhipov]

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