From NRA-ILA:

In response to the terrorist attack on military facilities in Chattanooga last year, the Air Force has reminded base commanders that they can authorize personnel to carry weapons on-duty and off-duty, and has established armed personnel programs to increase base security. Fox News reports, “the Unit Marshal Program enables commanders at every level to work with security forces to train Air Force members and allow them to open carry their [Beretta] M9 service pistol at their duty location. The Security Forces Staff Arming program enables more security officers to carry a government-issued weapon while on duty.”