Recently US Air Force personnel with responsibility for launching ground-based nuclear-tipped missiles twice in 2013 kept a blast door open in violation of security policy.

The blast doors at the subterranean installations – where intercontinental ballistic missiles are kept primed for firing – are not supposed to be kept ajar if any missileers inside are napping, in order to ensure an invader cannot seize the launch keys held by the Air Force officers.

The Air Force said in a statement that security of the ICBMs was not at risk following the April incident at Minot Air Force Base, North Dakota, and May incident at Malmstrom Air Force Base, Montana, “due to multiple safeguards and protections in place.”