US had been using eight zeros as the Minuteman Silos code for 20 years

To minimize any foreseeable delay in launching a nuclear missile during the height of the Cold War, the US military  intentionally set the launch codes at every silo in the US to 8 zeroes for nearly two decades.Every nuclear weapon the US had be fitted with a Permissive Action Link (PAL), basically a small device that ensured that the missile could only be launched with the right code and with the right authority, according to the the National Security Action Memorandum 160, which JFK signed in 1962.