For nearly 20 years, the secret code to authorize launching U.S. nuclear missiles, and starting World War III, was terrifyingly simple and even noted down on a checklist.
The Permissive Action Link (PAL) is a security device for nuclear weapons that it is supposed to prevent unauthorized arming or detonation of the nuclear weapon.
JFK signed the National Security Action Memorandum 160 in 1962 that required all nuclear missiles to be fitted with a PAL system.
But nuclear experts claim the military was worried about the possibility of command centers or communication lines being destroyed in real nuclear war, stopping soldiers getting the codes or authorization to launch missiles when they were actually needed.
So they simply left the security code for the weapons as eight zeros, getting around the security safeguards.
Dr. Bruce G. Blair, worked as a Minuteman launch officer between 1970 and 1974. He has written several articles about nuclear command and control systems.
In a paper called Keeping Presidents in the Nuclear Dark, he wrote that Strategic Air Command 'remained far less concerned about unauthorized launches than about the potential of these safeguards to interfere with the implementation of wartime launch orders.'
Incredibly, he also writes that the vital combination for America's nuclear deterrent was even helpfully noted down for the officers.
'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,' Dr Blair wrote.
According to Today I Found Out, Blair wrote an article in 1977 entitled The Terrorist Threat to World Nuclear Programs.
This claimed that it would take just four people working together to launch nuclear missiles from the silos he had worked in.
That very same year all the PAL systems were activated, and the nuclear codes were changed. Hopefully to something more complicated than 00000000.