Key findings in AP nuclear missile corps probe

Over the past three years, The Associated Press has documented evidence of security problems, low morale and other troubles in the nation's nuclear missile corps.

— In April 2013, 19 launch officers in the 91st Missile Wing at Minot Air Force Base, North Dakota, were taken off duty and given weeks of remedial training after being found unfit to perform. The wing's deputy commander of operations complained of "rot" in the force. The officer in charge of crew training and proficiency was fired.

— The 341st Missile Wing at Malmstrom Air Force Base, Montana, failed a safety-and-security inspection. Nine days later, the officer in charge of security forces was relieved of duty. The unit passed a do-over in October.

— An internal Air Force review of the Malmstrom inspection, obtained under the Freedom of Information Act, revealed that the inspection failed because security forces did not respond adequately to a simulated hostile takeover of a silo housing a nuclear missile. The Air Force implemented numerous corrective measures, mainly designed to increase and improve security forces training.

— Twice, the Air Force punished officers involved in separate incidents of opening the blast door of their underground launch control center while one of the two launch officers was asleep, in violation of Air Force rules.

— A Rand Corp. research study obtained by the AP found that missile corps members felt "burnout" from what they saw as exhausting, unrewarding and stressful work. The report also cited heightened levels of misconduct such as spousal abuse.

— In October 2013, the Air Force removed Maj. Gen. Michael Carey from command of the 20th Air Force, which is responsible for the entire Minuteman 3 missile force, for embarrassing, drunken behavior in Russia.

— In January 2014, dozens of missile launch officers were implicated in a cheating scandal at Malmstrom and were stripped of their certification in what the Air Force called the largest such breach of integrity in the nuclear force. The cheating involved the monthly test on their knowledge of how to operate the missiles. That scandal was revealed as part of a drug-use investigation that involved three ICBM launch officers.

— In late January 2014, Defense Secretary Chuck Hagel ordered an independent review of the nuclear force and summoned the most senior Pentagon leaders to discuss its missteps, leadership lapses and personnel problems.

— In March 2014, the Air Force fired nine midlevel nuclear commanders and supervisors, allowed a senior commander to resign and said it would discipline dozens of junior officers in response to the exam-cheating scandal at Malmstrom.

— On Nov. 3, 2014, the Air Force fired a missile squadron commander at Minot and reassigned the vice commander of the 90th Missile Wing at F.E. Warren Air Force Base in Wyoming to a non-command staff job. Also, a colonel in charge of all three missile squadrons at Minot was given administrative punishment but not removed from command.

— On Nov. 14, 2014, Defense Secretary Hagel ordered top-to-bottom changes in how the U.S. nuclear force is operated and managed. The changes came after a series of stories from the AP that revealed problems in the nuclear force's management and morale.

— On Jan. 22, 2016, the Air Force disclosed that errors by three airmen troubleshooting problems on a Minuteman 3 missile in its launch silo caused an undisclosed accident that damaged the missile. No one was hurt. The airmen were stripped of their certification to work with nuclear weapons for more than a year.

--On Friday, March 18, 2016, the Air Force said 14 security force airmen at the F.E. Warren nuclear missile base in Wyoming were under investigation for alleged illegal drug activity.