The Associated Press quotes Air Force officials who say officers with the launch keys for nuclear-tipped missiles opened blast doors in launch control facilities, in violation of Air Force policy.
Four officers received administrative punishment for violating the policy this year.
The A-P report says such incidents happened at missile control facilities controlled by Minot Air Force Base.
The blast doors are located far below the surface where the control capsule is located that included equipment for launching missiles.
Standard procedure for the Air Force requires that the door always be secured shut when there are crew members inside to prevent infiltration by terrorists or damage from attacks.