The real risk, embarrassingly enough, is accidental strikes. Amidst the chaos of an international crisis, global catastrophe could arise from a mere technological error — it only takes one falling domino to trigger an avalanche of self-defense responses, Bronson said. “We know the history. We know that conflict has the potential to escalate quickly,” she said. “When we have huge arsenals on high alert, accidents can happen that can be very dangerous.”

If this sounds more like “Dr. Strangelove” than reality, you may want to take a spin on the Wheel of Near Misfortune, where the Union of Concerned Scientists shares stories of instances where the world only narrowly avoided a nuclear strike. There have been a shocking number of close calls, where a faulty reading or hardware malfunction nearly provoked a nuclear response. Now swallow this: There’s nothing built into the system that has caused the coin to always come up heads so far. “We were prepared — and are still prepared — to use [nuclear] weapons at a moment’s notice,” said Schwartz. “The fact that we didn’t is not necessarily proof that the system works so much as proof that we got very lucky.”

If anything, we have reason to believe we won’t always be so lucky. “All of those incidents occurred during peacetime, so there were lots of indications that this is not normal,” said Schwartz. “If those kinds of incidents happen during a crisis, where everything is ratcheted up a few notches, and you’re already feeling kind of edgy, then not only are you perhaps convinced that it’s a real attack — as opposed to a glitch of some kind — but your system is geared to respond all the more rapidly.”