The US Air Force has removed 17 officers from the authority to control nuclear intercontinental ballistic missiles, US media have reported.
The unprecedented action was taken in April, after the unit’s deputy commander wrote in email the programme was suffering “rot”.
The story was first reported by the Associated Press.
The Air Force’s top official told a Senate hearing that the revelation shows it has strengthened inspections.
Michael Donley, the Air Force secretary, said he was confident that the nuclear missile force was secure.
In an email initially obtained by the AP, Lieutenant Colonel Jay Folds wrote that drastic action was needed because “we didn’t wake up” after an underwhelming inspection the month before.
The 91st Operations Group at Minot Air Force Base in North Dakota, the unit responsible for 15 Minuteman III missile launch control centres, received an satisfactory review overall in March.
But the unit received the equivalent of a D grade on the test of its mastery of the missile launch operations.
Lt Col Folds also complained of unwarranted questioning of orders by launch crews and the failure of more senior officers to report infractions.
“We’re discovering such rot in the crew force,” he wrote, that the unit was accepting violations of safety rules and code compromises “all in the name of not inconveniencing yourselves”.
The 17 officers were removed from duty of 24-hour shifts watching over nuclear missiles that can strike targets across the globe. Inside each underground launch control capsule, two officers stand “alert'” at all times, ready to launch an ICBM upon presidential order.
The Air Force said the lapses never put the security of the nuclear force at risk and that the officers pulled from the watch will receive more training. They are expected to return to normal duty within two months.
The service has removed officers from nuclear authority before, but never so many at one time.
The move comes after a 2008 Pentagon report excoriated the Air Force for a series of blunders, including a bomber’s mistaken flight across the country armed with nuclear-tipped missiles.
The top civilian and military leaders of the Air Force resigned over the report.
It had taken numerous steps since then to improve the force’s nuclear performance.
At a Senate hearing Wednesday, Mr Donley, said the launch control officers were relatively junior in rank and need to be reminded continually of the importance of “this awesome responsibility”.
Air Force Secretary Michael Donley said the nation’s nuclear missile force is secure
The air force’s chief of staff also endorsed the handling of the situation by Minot Air Force base officials and said it had been “more of an attitude problem than a proficiency problem”.
But at least one Senator was not calmed by official assurances. Illinois Democrat Richard Durbin, chairman of the Senate Appropriations defense subcommittee, expressed outrage, saying the AP report revealed a problem that “could not be more troubling”.
Bruce Blair, who served as an Air Force ICBM launch control officer in the 1970s and is a co-founder of nuclear weapons elimination group Global Zero, said the email points to a broader problem.
“The nuclear air force is suffering from a deep malaise caused by the declining relevance of their mission since the Cold War’s end over 20 years ago,” Mr Blair said.
“Minuteman launch crews have long been marginalised and demoralised by the fact that the Air Force’s culture and fast-track careers revolve around flying planes, not sitting in underground bunkers baby-sitting nuclear-armed missiles.”
Right, we don’t want any questioning of orders when it comes time for a big mass murder.