I am sure you have heard of the economic damages caused by seemingly innocuous software bugs. But have you heard of the software bug which could have changed the course of history?

This is the story of how a software bug caused the USSR to almost launch a nuclear attack on the US.

The Incident

On the night of September 23, 1983, Stanislav Petrov, an officer on duty, was in command of early warning systems that detected incoming ICBMs with the help of the satellites. These satellites were operated by a software program named OKO.

The USSR implemented the early warning system in a hurry due to the ongoing tensions with the US; this meant the system could have some vulnerabilities. The final call, therefore, was to be taken by the officer in command. If a commanding officer detected an incoming ICBM, they must report the incident to their superiors. The superiors would then retaliate, starting a potential all-out war.

Sometime after midnight, the computers at the command center started to warn of an incoming ICBM; Stanislav Petrov found this as an odd occurrence, as it was expected that a first nuclear strike would include hundreds of ICBMs at the same time. So, he decided to rule it out as a false alarm.

Within a few minutes, the computer warned again with four more ICBMs heading towards USSR. Again, this was an odd occurrence; but if it were true, it could lead to thousands being killed. Stanislav Petrov had to make a call, but he was unsure if this was an actual attack and decided to wait for warnings from other systems as well.

If this were an actual nuclear attack, a few minutes would make a massive difference as the first attack will most likely determine the war’s outcome.

As time passed, there were no other warnings from the ground systems in place. So Stanislav Petrov decided to rule this out as a false alarm.

Later, the analysis found that the system mistook a rare alignment of sun rays on high-altitude clouds as the fumes from an incoming ICBM.

The defect in the system was never officially recognized, and as per few sources, Petrov took early retirement due to a nervous breakdown.


We are more exposed to software bugs than we think. A minor defect in the system can lead to catastrophic damages. Luckily it was prevented. Had it not been for Petrov, the world would have been a completely different place.

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