File photo showing a retired Minuteman 1 missile stands at the main entrance to Minot Air Force Base, North Dakota.
CNN  — 

Two US Air Force commanders and four of their subordinates at a key nuclear base in North Dakota were relieved of duty this week after their units failed an inspection designed to ensure that the nuclear weapons stockpile is safe and secure at all times, two defense officials told CNN.

The removals occurred at Minot Air Force Base, which is the only Air Force installation that houses two legs of the “nuclear triad” – ballistic missile silos and strategic bombers. The officials told CNN that the six service members were relieved of duty following the failed nuclear surety inspection at the base.

The nuclear surety inspection is a pass/fail test and the results are classified.

There is no indication that the failed inspection was related to the handling of a nuclear weapon itself. Another defense official said the failure was for “non-compliance vehicle and equipment safety inspections.”

Colonel Brus E. Vidal, director of public affairs at the Air Force Global Strike Command, would not confirm the specific nature of the inspection.

“We have deliberate and disciplined inspection protocols and we expect 100% compliance,” Vidal told CNN. “Anything less than 100% compliance is unacceptable. It’s that important to us.”

The commander of the 5th Mission Support Group and the commander of the 5th Logistics Readiness Squadron were relieved of command. The Mission Support Group, consisting of 1600 military and civilian personnel, is in charge of caring for base facilities, infrastructure and troops. The Logistics Readiness Squadron is in charge of things like planning deployments and managing supply chains.

The doctrine of nuclear surety is designed to check that the US nuclear stockpile is safe, secure, and under positive control. The inspection tests the ability of different units to carry out their mission related to nuclear weapons, as well as the ability to handle and maintain nuclear weapons and the chain of command around the strategic weapons.

The exact circumstances surrounding the failed nuclear safety inspection at Minot remain unclear but Air Force Global Strike Command made clear in a statement Monday that the commanders were relieved “due to a loss of confidence in their ability to complete their assigned duties.”

“These personnel actions were necessary to maintain the very high standards we demand of those units entrusted with supporting our nation’s nuclear mission,” Maj. Gen. Andrew J. Gebara, commander of 8th Air Force, said at the time.

Gebara vowed that the Eighth Air Force “continues to safeguard global combat power and conduct around-the-clock strategic deterrence operations in a safe, secure and effective manner. Our mission is foundational to our Nation’s defense, and we remain committed to the success of that no-fail mission.”

This is not the first instance of a failure of the nuclear surety inspection. In 2013, an Air Force nuclear missile unit at Malmstrom Air Force base in Montana failed a safety and security inspection, according to an Air Force statement at the time.

The wing received an “unsatisfactory rating” after making “tactical level errors” during one of several exercises conducted as part of the inspection, the statement said.

The results of these inspection tests were made classified in 2017 after officials determined that releasing the test results could reveal potential vulnerabilities to the US’ enemies.