WASHINGTON (AP) — Failings exposed last spring at a U.S. nuclear missile base, reflecting what one officer called “rot” in the ranks, were worse than originally reported, according to Air Force documents obtained by The Associated Press.

Airmen responsible for missile operations at Minot Air Force Base, N.D., would have failed their portion of a major inspection in March 2013 but managed a “marginal” rating because their poor marks were blended with the better performance of support staff — like cooks and facilities managers — and they got a boost from the base’s highly rated training program. The “marginal” rating, the equivalent of a “D” in school, was reported previously. Now revealed are details of the low performance by the launch officers, or missileers, entrusted with the keys to missiles.