A security group commander at North Dakota's Minot Air Force Base was relieved of his command Wednesday after explosives and a machine gun were lost in separate incidents.

Col. Jason Beers of the 91st Security Forces Group was ousted because the Air Force had lost trust and confidence in him, said Col. Colin Connor, commander of the 91st Missile Wing.

The Minot base, home to about 4,800 active-duty military personnel, is one of the nation's two B-52 bomber bases and the command center for about 150 Minuteman III missiles, housed underground in hardened silos across 8,500 square miles of northwest and north-central North Dakota.

An M240 machine gun was discovered missing May 16 during a routine weapons inventory earlier this month. Separately, the military last week called off a search of a container of ammunition for an automatic grenade launcher. Authorities said the explosives fell off a Humvee May 1 on the Fort Berthold Indian Reservation near Parshall, in the northwest part of the state.

The military said the base is taking inventory of all its weapons due to the loss of the gun.

The North Dakota base has been under scrutiny for years, following a 2007 mishap in which a B-52 bomber was mistakenly armed with six nuclear-tipped cruise missiles in Minot and flown to Barksdale Air Force Base in Louisiana.

Other lapses at the base followed the bomber flight, including two crashes of vehicles carrying missile parts within a year of each other, the theft of a launch code device, the discovery of missile crew members sleeping on the job and failed inspections.

In 2014, Army Gen. Martin Dempsey, then-chairman of the Joint Chiefs of Staff, told hundreds of Minot airmen that nuclear weapons missteps would be corrected, but he didn't elaborate on the "failures of leadership" he blamed for causing the problems.