Air Force Secretary Deborah Lee James said she returned from a visit to missile bases convinced there were "systemic problems" among crew members related to morale, referring to a climate of "undue stress and fear."
"As the investigation has moved forward, we can now report there is a total of 92 crew members that have been identified as having some level of involvement," James told a news conference.
"That means either participating in the cheating or knowing something about it and not standing up and reporting it," she said.
The mounting scandal, as well as other incidents, have prompted commanders to put a hold on any promotions of senior officers in the nuclear mission, a defense official, who spoke on condition of anonymity, told AFP.
Also Read
"They're reviewing all of those (proposed promotions)," the official said.
The cheating was discovered when criminal investigators looking into illegal drug possession among missile launch officers stumbled upon evidence of cheating on a monthly proficiency test at the Montana base.
The investigators found one officer had the answers to a monthly proficiency test on his mobile phone and had sent them to his fellow crew members.