The United States nuclear missile force has been hit by scandal after 34 officers were removed from duty for their alleged involvement in a cheating ring.
The US Air Force said on Wednesday that 34 intercontinental ballistic missile (ICBM) officers at Malmstrom Air Force Base, Montana, were either sharing material or were aware that material was being shared on proficiency tests.
Air Force Secretary Deborah Lee James, who described the behaviour as "completely unacceptable", said the cheating ring was uncovered during a drug possession investigation involving 11 officers at several US Air Force bases, with two of the 11 also suspected of participating in the cheating ring.
A spokesman for US Defence Secretary Chuck Hagel said the Pentagon chief was "deeply troubled" to learn of the allegations and that he supported the "aggressive steps" the Air Force was taking in response.
The cheating scandal is the latest in a series of controversies affecting the US nuclear missile force.
According to the Associated Press news agency, others include deliberate violations of safety rules, failures of inspections, breakdowns in training, and evidence that the men and women who operate the missiles from underground command posts are suffering from burnout.
In October the commander of the nuclear missile force was dismissed for engaging in embarrassing behavior, including drunkenness, while leading a US delegation to a nuclear exercise in Russia.
James said on Wednesday: "I want all of you to know that, based on everything I know today, I have great confidence in the security and the effectiveness of our ICBM force.
"And, very importantly, I want you to know that this was a failure of some of our airmen. It was not a failure of the nuclear mission."
James said the entire ICBM launch officer force of about 600 people was being retested this week.