One frightening incident that is quite well known occurred on September 26, 1983. In that incident, there was a gentleman named Stanislav Petrov, who was a Lieutenant Colonel in the Soviet Air Defense Forces who was serving as the senior duty officer in charge of the command center at a Soviet early warning bunker (known as "Serpukhov-15").

During his duty shift that day, the Soviet Union's Oko early-warning satellite system made a detection that it erroneously interpreted as being an incoming ballistic missile launch. Thankfully, Petrov did not believe the warning to be authentic, and going against well established procedures, he refused to immediately notify his higher-ups in the military or Politburo political apparatus.

Interestingly, the reason Lieutenant Colonel Petrov did not believe the launch warning datastream coming in from the Oko satellite was because luckily, he had actually been heavily involved in monitoring the development of the Soviet Oko early warning satellite constellation since its earliest design days, and he knew it was a very poor, unreliable system and could not be trusted because, contrary to what the Soviets publicly claimed about Oko at the time, it was highly prone to the threat of false-positive detections.

The Oko satellite constellation did not actually detect the initial launch of a nuclear missile, but rather their orbital placement had these sats flying in highly elliptical "Molniya" orbits. This orbital profile allowed the satellites to observe the United States missile fields from high-oblique "look angles", meaning they observed the target area from the side rather than overhead, looking for telltale infra-red signatures from the rocket motors. Rather than using radar or looking to detect a missile visually as it launched, the idea behind Oko was that once the nuclear missile had reached high altitude and its look angle breached the Earth's horizon in relation to the Oko satellite, Oko's onboard IR detection system would be able to detect the heat signature from the rocket propelling the missile as it burned hot and bright against the cold stellar backdrop of space.

In the case of this famous incident, there happened to be some high-altitude clouds above the US missile fields that this specific Oko sat was monitoring at the time, and due to the coincidental location of the sun at this instant, these cloud tops actually reflected the sunlight directly at the Oko satellite onboard IR sensor array. The Oko satellite sensors detected that sudden infra-red bright spot "bloom" and, as it was programmed to do, the early-warning satellite interpreted that as an incoming missile and triggered the alarm.

Colonel Petrov was notified of the detection immediately since he was the senior duty officer at Serpukhov-15, and due to his experience with the very low reliability of the Oko system, and from the fact that it was initially only detecting a single IR bloom (signifying only one initial missile detection as opposed to a salvo of many missiles), he concluded that it was most certainly a false positive detection situation. He decided to wait for radar confirmation (which of course never came) before going up the chain of command with the news, and part of the reason for that, Petrov has admitted since, is because he was not sure due to the political climate at the time how the Soviet Politburo political leadership in charge would react. At the time of this incident, tensions between the USA and USSR were rather high, and had been increased further just a few weeks prior because the Soviet military had shot down Korean Air Lines Flight 007, killing 269 civilian passengers and crew.

In regards to this incident, it is worth noting that unlike the USA, the Soviets did not have extensive near-global radar confirmation capability at that time (and they really still don't). Petrov had to actually wait for quite awhile after the Oko satellite sounded the initial incoming launch alarm that was triggered by its IR sensors before the nuclear missile (which did not exist) would have been close enough to Soviet-controlled airspace that they would have a direct line-of-sight on it to use radar to either confirm the incoming missile, or confirm the Oko detection as a false positive. Obviously, that radar confirmation of an incoming missile never came because there was no incoming missile.

Petrov's real heroics in that incident was waiting for the radar confirmation before going up the chain of command. He has stated in interviews since that he was sure it was a false positive, and was not at all surprised when the radar screen never picked up a track of anything incoming. At the time, there was a lot of strife within the Soviet political apparatus, and Petrov was well aware of that in-fighting that was going on due to his position as a high-ranking military officer. He simply did not trust the ability of the Politburo higher-ups to (in just the few short minutes they would be given to react) properly weigh the evidence, take into account the reality that the Oko constellation design flaws were so great that the satellites could not be trusted to provide accurate data, then make the correct decision and chose not to order a retaliatory strike before the supposed incoming non-existent missile struck Soviet territory. The MAD doctrine and Soviet planned counter-response to a US first strike scenario required that the USSR try to get at least a portion of their retaliatory strike fired off before any incoming missiles impacted their soil, and Petrov felt that more than a few politicians and military men would have pushed hard to order the launch of a retaliatory strike in those few short minutes they would have had to decide.

What really took a lot of balls was when the Oko alarms went off at Serpukhov-15 and Petrov - a career military man - deliberately chose to not follow the very explicit orders he had which demanded he pick up the red phone and immediately notify Moscow that one of the early-warning satellites was signaling a launch detection and incoming missile from the USA. He knew that HUGE act of disobedience could have ended his career in a heartbeat once it was found out (and maybe even put him in a gulag somewhere in Siberia), but he also knew the signal from the Oko bird had a very high probability of being a false positive and that there was no real threat.

Luckily, after the news of this false positive detection incident came out, many within the Politburo realized that punishing Petrov for disobeying his orders would have negative propaganda results, and since his decision was the right one, they ended up letting his disobedience slide.

I thought of another example in addition to the one involving Stanislav Petrov and the Oko satellite I mentioned in that early post.

In this instance, it was not actually during the Cold War, but took place afterwards, and it did not involve the USSR, but rather involved Russia - though it was a very dangerous incident as well, so I hope you don't mind me mentioning it here (as it does still adhere to this subreddit's 20 year rule).

It took place back in 1995, and came to be known as the "Black Brant Scare" - also called the Norwegian rocket incident - where Norwegian and American scientists launched a four-stage sounding rocket from Norway in an attempt to study the Aurora Borealis.

During that incident, the Black Brant XII sounding rocket flew a high apogee up-and-down profile that was somewhat similar to that which a Trident nuclear missile could typically employ to deploy a first-strike EMP (Electro-Magnetic Pulse) burst.

The Russians detected the launch of this rocket with their early-warning radar once they were able to gain line-of-sight of it as the booster climbed out of Norway, and unfortunately, even though the USA and Norway had followed proper agreed upon procedures and had notified the Russian authorities of the scheduled launch well ahead of time, the Russian military had a communication breakdown that resulted in their commanders and radar operators at their command and control early warning bunkers never getting informed of this harmless scientific launch.

In this "Black Brant" case, it was such a screwup of communications breakdowns on the part of Russia that Boris Yeltsin, the Russian President at the time, actually was notified immediately (as per protocol) and Yeltsin even opened up and activated his "nuclear briefcase", which has the codename "Cheget" (The US nuclear briefcase counter-part to this system is called "Football", and it, like its Russian counterpart, accompanies the President everywhere he goes). This activation of the "Cheget" briefcase was done so Yeltsin could prepare to launch a counter-attack against the USA, because they thought this harmless scientific launch they detected might actually have been an early first strike EMP attack from the USA.

Luckily, cooler heads prevailed in this incident (which frankly was, in my opinion, worse and brought us closer to nuclear war than the earlier "Oko" debacle I described in my earlier post), but not before Yeltsin had activated the "Cheget" briefcase system, and not before commands had been sent to Russian subs and land-based missile facilities to be prepared for a retaliatory strike against America.

During the "Black Brant Scare" incident, the fact that the rocket was launched from Norway was very frightening to the Russians, because the Russian communications failures meant those running the early warning bunkers did not realize the launch was going to happen ahead of time so they were not ready and waiting to properly track its trajectory, and because of that they could not initially tell if the missile was even launched from Norway soil proper or whether it maybe came from just offshore from a US ballistic missile submarine. As the scientific rocket climbed to high apogee, its flight profile was somewhat similar to that predicted for a high-altitude EMP burst targeting Russia, so it caused a hell of a lot of concern and panic. If the Russian command and control had of known about the launch ahead of time as they should have, they would have been in a better state to properly track the rocket immediately and would have been better able to quickly determine its safe trajectory and obvious non-hostile intent.

It gets even more scary when you realize that at the time of the "Black Brant Scare", there was a good chance that Boris Yeltsin was hammered drunk and was not exactly a clear-minded guy, yet he was the one at the top of the Russian nuclear arsenal's retaliatory command structure.