The Strategic Air Command (SAC) in Omaha quietly decided to set the “locks” to all zeros in order to circumvent this safeguard. During the early to mid-1970s, during my stint as a Minuteman launch officer, they 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 dialled 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 0000000.
Well, I certainly feel safer. It reminds me a little of the probably apocryphal story that, during the Nixon administration, the SAC had a standing order to ignore any requests to launch missiles if they came from The Oval Office after 6:30pm, as Nixon liked to get drunk and plunge us all into ash.