Apparently, during the 1960s, Minuteman ICBMs had something called “permissive action locks” installed on them to prevent accidental firing; but according to this piece, the initial combination was set to “00000000” and never changed. Why? Because “the Strategic Air Command (SAC) in Omaha quietly decided to set the “locks” to all zeros in order to circumvent this safeguard.” According to someone who was stationed there during the 1970s, the codes
still had not been changed. Our launch checklist in fact instructed us, the firing crew, to double-check the locking panel in our underground launch bunker to ensure that no digits other than zero had been inadvertently dialed into the panel. SAC remained far less concerned about unauthorized launches than about the potential of these safeguards to interfere with the implementation of wartime launch orders. And so the “secret unlock code” during the height of the nuclear crises of the Cold War remained constant at OOOOOOOO.
[To the tune of The Police, “Bombs Away,” from the album Message In A Box: The Complete Recordings (Disc 2).]