US Air Force fires missile officers

The US Air Force has sacked nine nuclear missile officers and will discipline dozens more over an exam cheating scandal.

The officers, including four squadron chiefs, were all working at Malmstrom Air Force base in Montana, which has been rocked by cheating allegations implicating up to 100 airmen.

"Nine officers in leadership positions at Malmstrom were recommended for removal," Air Force Secretary Deborah James told a news conference on Thursday.

An internal investigation found the commanders didn't engage in any test cheating but "failed to provide adequate oversight of their crew force", James said.

A tenth officer has submitted his resignation over the case.

A top general overseeing nuclear forces said the cheating stemmed in part from a stifling atmosphere created by commanders who over-emphasised perfect test scores.

"Although the required test score is 90 per cent, crew members felt pressure to score 100 per cent on each and every test," Lieutenant General Stephen Wilson said at the same news conference.

"They felt compelled to cheat to get a perfect score," he said.

The "zero-defect" approach was unrealistic and unnecessary, as the rules for managing the ballistic missiles had redundancies and other automatic safeguards, Wilson said.

"Leaders lost sight of the fact that execution in the field is more important than what happens in the class room," he said.

The cheating was first uncovered in January during an unrelated investigation into illegal drugs, the outcome of which is still pending.

Out of 100 officers potentially linked to the cheating, nine have since been cleared in an investigation.

Another nine cases are being examined separately by the Air Force Office of Special Investigations. Of those, eight could involve criminal charges related to mishandling classified information - possibly the exam materials.

About 30 to 40 officers will be retrained and allowed to return to duty, while the remainder will face disciplinary action.