Lawmakers asked after media reports last year.
The Pentagon has denied to Congress that it ever established a nuclear missile launch code of "00000000," despite earlier reports, according to Foreign Policy.
The House Armed Services Committee had demanded to know whether media reports were accurate that from 1962 to 1977, the Air Force used an eight-zero authorization code for the launching of strategic missiles. The source of the reports was former ICBM launch officer Bruce Blair, who went on to found Global Zero -- a movement that urges the total elimination of nuclear weapons.
"A code consisting of eight zeros has never been used to enable a MM ICBM, as claimed by Dr. Bruce Blair," the military reportedly said in its response to Congress, apparently referring to Minuteman ground-based missiles. Foreign Policy said it had viewed the correspondence to Capitol Hill.
Blair in a 2004 essay alleged that the Air Force had violated the spirit of President Kennedy's 1962 directive to put in place additional authorization requirements to minimize the chances of an unauthorized or accidental missile launch. The Air Force, according to Blair, chose to install the eight-zero passcode as it was more concerned with hurdles to a timely ICBM launch than an unintentional missile firing.