The Air Force base that sparked a controversy last year because its B-52 crews unknowingly flew nuclear missiles has failed a nuclear security test from Defense Department inspectors.

Personnel at the 5th Bomb Wing's Minot Air Force Base here failed to counter simulated nuclear security challenges that earned it an "unsatisfactory" grade in that category from inspectors on Sunday, based on a report of the Pentagon's Defense Threat Reduction Agency that was cited on the Air Force Times website. The tests were conducted for a week starting May 17.

Among the lapses were a guard playing games on his cell phone while on duty, an airman unaware of her duties and responsibilities, security forces that did not clear a building they entered or properly check a vehicle entering a nuclear storage area, failure to use the right password to enter restricted areas, and airmen who did not understand key nuclear terminology.

The inspection team attributed the lapses to improper supervision of the airmen.

However, the Air Force base got a satisfactory rating in the nine other areas that were inspected, including its safety and technical operations conduct, according to the report.