At the height of the Cold War between the US and the Soviet Union, each had made sure that if their country was to fall to nuclear destruction, it would take the other with it. That was “deterrence,” the idea that if a country had the ability to retaliate in a way that was almost unthinkable — guaranteed nuclear annihilation — no one would dare attack them. Underground missile silos filled with nuclear warheads pre-programmed to target major cities was that deterrence.

In a new video from the fantastic YouTube science channel Veritasium, Derek brings us underground and runs through the actual firing sequence for a Cold War nuclear missile. He visits Chuck Penson at the Titan Missile Museum in Arizona, who leads him through a non-functional procedure for ending the world as we know it. There are codes, spring-loaded keys that two people must turn, and a surprising amount of drama.

But of course, everything is dramatic when a nuclear winter is a few button presses away.

“That button should say ‘Welcome to World War III’.” Jeez.