Updated

Service leaders took an assessment last year of the nuclear Air Force as an encouraging thumbs-up. Yet, in the months that followed, signs emerged that the nuclear missile corps was suffering from breakdowns in discipline, morale, training and leadership.

The former Air Force chief of staff who signed off on the 2013 report is now being asked to dig for root causes of problems that Defense Secretary Chuck Hagel says threaten to undermine public trust in the nation's nuclear arsenal.

The Air Force may have taken an overly rosy view of the report by a Pentagon advisory group headed by retired Gen. Larry Welch. The inquiry itself may have missed signs of the kinds of trouble documented in recent months in a series of Associated Press reports.