WASHINGTON (AP) — An Air Force document obtained by The Associated Press says armed security forces at a nuclear missile base failed a drill last summer that simulated the hostile takeover of a missile launch silo.

It says the security troops failed to speedily regain control of the captured nuclear weapon.

The previously unreported failure — which the Air Force called a "critical deficiency" — was the reason the 341st Missile Wing at Malmstrom Air Force Base in Montana flunked its broader safety and security inspection.

The partially censored document obtained by the AP did not fully explain the problem. It said the security team did not take "all lawful actions necessary to immediately regain control" of the silo. A do-over of the test two months later was performed without any reported problems.