On Sept., 26, 1983, shortly after midnight, the Soviet Oko nuclear early warning system detected five missiles launched from the United States and headed toward Moscow. Stanislav Petrov, a young lieutenant colonel in the Soviet Air Defense Force, was the duty in the Serpukhov-15 bunker that housed the Oko command center. Petrov was the man in charge of alerting the soviets about a nuclear attack, which would trigger a retaliatory strike. He determined that the Oko had likely malfunctioned and the alarm was false. The Americans would not start World War III with a quintet of missiles (risking total annihilation.) It was a daring judgment call. He was, of course, right. As the U.S. prepares to undertake a new nuclear posture review to determine the future direction of the nation’s nuclear weapons, a report from a United Nations research institute warns that the risks of a catastrophic error — like the one that took place that early morning in 1983 — are growing, not shrinking. Next time, there may be no Lt. Col. Petrov in place to avoid a catastrophe.

On Monday, the U.S. Defense Department commenced a new, massive study into its nuclear weapons arsenal, looking at how weapons are kept, how the U.S. would use them in war and whether they present an intimidating enough threat to other countries not to attack us. The review was mandated by President Trump in a Jan 27, memo.