WASHINGTON — The Air Force has fired or disciplined at least 16 nuclear missile commanders or senior officers for misconduct and other failings over the past year and a half, reflecting turmoil in arguably the military’s most sensitive mission.

Another who quit of his own accord lamented upon leaving, “We let the American people down on my watch.”

The latest to be dismissed this week: a colonel accused of “cruelty and maltreatment” of a subordinate and a missile squadron commander found to have illegally discriminated against women under his command. In addition to those actions Monday, another senior officer was administratively disciplined but not removed from command.

This string of leadership lapses has beset a force that remains central to American defense strategy but in some respects has been neglected. The force of 450 Minuteman 3 nuclear missiles is primed to unleash nuclear devastation on a moment’s notice.

On Monday the Air Force confirmed to The Associated Press that it had removed Col. Carl Jones as vice commander of the 90th Missile Wing at F.E. Warren Air Force Base, Wyoming, in charge of 150 Minuteman 3 missiles. He was dismissed “for a loss of trust and confidence in his leadership abilities,” and has been reassigned as a special assistant to the wing commander.

The actions were disclosed in response to an AP inquiry about an internal Air Force investigation of two commanders at the 91st Missile Wing at Minot Air Force Base, North Dakota, which also is responsible for 150 Minuteman 3 missiles.

Lt. Col. John Sheets, spokesman for Air Force Global Strike Command, said that as a result of the Minot investigation a missile squadron commander, Lt. Col. Jimmy “Keith” Brown, was relieved of command Monday “because of a loss of confidence in Brown’s ability to lead his squadron.”

Sheets said the investigation was directed by Maj. Gen. Jack Weinstein, commander of the 20th Air Force, and “substantiated that Brown engaged in unlawful discrimination or harassment.” The probe found that Brown “made statements to subordinates that created a perception within his squadron that pregnancy would negatively affect a woman’s career.”

The probe also said Brown had failed to ensure the well-being of his troops. In March a two-person crew operating a Minuteman 3 launch control center at Minot felt ill from fumes, but the crew remained at their post because they believed Brown would have taken action against them had they left. They later were hospitalized, Sheets said.

Col. Richard Pagliuco, commander of the 91st Operations Group, in charge of the three missile squadrons at Minot, including Brown’s, “failed to promote and safeguard the morale, well-being and welfare of the airmen under his command,” Sheets said.

The complaints against Jones, the vice commander of the 90th Missile Wing at F.E. Warren, were the most extensive, according to Sheets.

Sheets said Jones’ superior removed him following an internal probe that substantiated allegations of conduct unbecoming an officer and a gentleman, and cruelty and maltreatment of a subordinate.

The most recent incident was one in which Jones went to a thrift store operated on F.E. Warren by volunteers – Airman’s Attic – to discuss the store’s hours. “He hit the sign on the Airman’s Attic door and repeatedly hit the shop’s front counter while raising his voice, using profanity” and threatening to shut down the place, Sheets said.

Three other incidents of allegedly inappropriate behavior on base by Jones were substantiated in the investigation.

These were the latest in a string of at least 16 firings or disciplinary actions against senior nuclear officers that began in June 2013.