The failure was recorded by the 341st Missile Wing at Malmstrom Air Force Base, Mont., which is responsible for 150 Minuteman 3 nuclear missiles that stand on 24/7 alert for potential launch against targets around the globe.
Lt. Gen. James M. Kowalski, commander of Air Force Global Strike Command, which is responsible for the Minuteman 3 force as well as nuclear bombers, said the 341st wing failed a "small team exercise" as part of a broader inspection. The exercise failure meant the whole inspection was a failure, he said.
Kowalski said this did not call into question the unit's safe operation of nuclear missiles but was its second failure of a safety and security inspection in just over three years.
"I wouldn't necessarily call it a pattern," he said, since a large number of those involved in the latest inspection were not there for the previous failure in February 2010.
Kowalski would not discuss details of the failure or explain the exercise, citing security, except to say that it did not involve the crews who monitor the missiles from inside underground launch control capsules. That left open the possibility that it involved airmen responsible for security, weapons maintenance or other aspects of the highly sensitive mission.
"This unit fumbled on this exercise," Kowalski told the AP by telephone from his headquarters at Barksdale Air Force Base, La.
In a written statement posted to its website, Kowalski's command said there had been "tactical-level errors" during the exercise, revealing "discrepancies."
Without more details it is difficult to make a reliable judgment about the extent and severity of the problem uncovered at Malmstrom. Asked whether the Air Force intends to take disciplinary action against anyone as a result of the inspection failure, Kowalski said the Air Force is "looking into it."
He said those who failed the exercise would be retested within three months.
This is the second major setback this year for the Air Force's nuclear weapons force. Last spring the 91st Missile Wing at Minot Air Force Base, N.D., received weak grades on an inspection but did not fail it outright; that performance was so poor, however, that 17 officers temporarily lost their authority to operate missiles.