US Air Force officers entrusted with the launch keys to nuclear-tipped missiles have been caught twice this year leaving open a blast door intended to help prevent a terrorist or other intruder from entering their underground command post, it has emerged.
The blast doors are never to be left open if one of the crew members inside is asleep - as was the case in both these instances - out of concern for the damage an intruder could cause, including the compromising of secret launch codes.
Transgressions such as this are rarely revealed publicly, but officials with direct knowledge of air force intercontinental ballistic missile operations said such violations had happened, undetected, many more times than in the cases of the two launch crew commanders and two deputy commanders who were given administrative punishments this year.
The blast door breaches are another sign of serious trouble in the handling of America's nuclear arsenal. The Associated Press news agency discovered a series of problems within the ICBM (Intercontinental Ballistic Missile) force, including a failed safety inspection, the temporary sidelining of launch officers deemed unfit for duty and the abrupt sacking last week of the two-star general in charge.
The problems, including low morale, underscore the challenges of keeping safe such a deadly force that is constantly on alert but unlikely ever to be used.
The crews who operate the missiles are trained to follow rules without fail, including the ban on having the blast door open when only one crew member is awake, because the costs of a mistake are so high.
The officers, known as missileers, are custodians of keys that could launch nuclear hell. The warheads on the business ends of their missiles are capable of a nuclear yield many times that of the atomic bombs dropped on Japan in 1945.
"The only way that you can have a crew member be in 'rest status' is if that blast door is shut and there is no possibility of anyone accessing the launch control centre," said Lt Gen James Kowalski, the commander of Air Force Global Strike Command, responsible for the entire force of 450 Minuteman 3 missiles, plus the US Air Force's nuclear-capable bombers.
The written air force instruction on ICBM weapon safety, last updated in 2011, says: "One crewmember at a time may sleep on duty, but both must be awake and capable of detecting an unauthorised act if ... the Launch Control Centre blast door is open" or if someone other than the crew is present.
Each underground launch centre, known as a capsule for its pill-like shape, monitors and operates 10 Minuteman 3 missiles.
The missiles stand in reinforced concrete silos and are linked to the control center by buried communications cables. The ICBMs are split evenly among "wings" based in North Dakota, Wyoming and Montana. Each wing is divided into three squadrons, each responsible for 50 missiles.
In neither of the two reported violations was security of the crews' missiles compromised, the air force said, "due to the multiple safeguards and other protections in place". But they were clear-cut breaches of what the air force calls "weapon system safety rules" meant to be strictly enforced in keeping with the potentially catastrophic, consequences of a breach of nuclear security.
In the two episodes confirmed by the air force, the multi-ton concrete-and-steel door that seals the entrance to the underground launch control centre was deliberately left open while one of two crew members inside napped.
One officer lied about a violation but later admitted it.
Sleep breaks are allowed during a 24-hour shift, known as an "alert". But a written rule says the door - meant to keep others out and to protect the crew from the blast effects of a direct nuclear strike - must be closed if one is sleeping.
In an interview last week at his headquarters at Barksdale Air Force Base, Louisiana, Lt Gen Kowalski declined to say whether he was aware that ICBM launch crew members had broken the blast door rule with some frequency.
"I'm not aware of it being any different than it's ever been before," he said. "And if it had happened out there in the past and was tolerated, it is not tolerated now. So my sense of this is, if we know they're doing it they'll be disciplined for it."
But it is clear that air force commanders know the incidents are happening. One of the officers punished for a blast door violation in April at the 91st Missile Wing at Minot Air Force Base, North Dakota, admitted during questioning by superiors to having done it at other times without getting caught.
Both officers were given what the military calls non-judicial punishment under the Uniform Code of Military Justice, rather than court martialled.
One was ordered to forfeit 2,246 dollars in pay for two months and received a letter of reprimand, according to Lt Col John Sheets, spokesman for Air Force Global Strike Command. The other launch officer, who admitted to having committed the same violation "a few" times previously, was given a letter of admonishment.
The other confirmed blast door incident happened in May at Malmstrom Air Force Base, Montana. The deputy crew commander initially denied the accusation but later confessed and said her crew commander had encouraged her to lie, Lt Col Sheets said.
The crew commander was ordered to forfeit 3,045 dollars in pay for two months and also faces an air force discharge board which could force him out of the service. The deputy crew commander was given a letter of reprimand.