Despite their increasingly sophisticated decision-making abilities, AI systems still need human inputs. In 1983, during a period of high Cold War tensions, Soviet information systems abruptly sounded an alert that warned of five incoming nuclear missiles from the United States. A lieutenant colonel of the Soviet Air Defense Forces, Stanislav Petrov, faced a difficult decision: Should he authorize a retaliatory attack? Fortunately, Petrov chose to question the system's recommendation. Instead of approving the retaliation, he decided that a real attack was unlikely based on several outside factors -- one of which was the small number of "missiles" reported by the system -- and moreover, even if it was real, he didn't want to be the one to complete the destruction of the planet.