[3] Crew size varies among the different missile systems, but the number is always greater than one, to abide by USSTRATCOM's two-man rule for positive control of nuclear weapons.
From the early days of United States missile crew operations until the late 1970s, the career field was closed to female personnel.
UQT/UOT was held at the missile base(s) the personnel was assigned to, and conducted by local instructors, lasting three or four weeks.
Crews would gather on the base, receive briefings and equipment, and travel out to their alert location by either truck or helicopter.
Early missiles such as Thor and Atlas, relied on support facilities above ground, with crews protected in a shelter of some sort.
Later systems were buried underground, either with the missiles located nearby (i.e. Titan) or a distance away (Peacekeeper, Minuteman).
In the underground environment, crews dealt with artificial lighting, recycled air, loud noises, and intimately close quarters (in Minuteman and Peacekeeper) with equipment racks.
The land-based deterrent, consisting of Hadès and SSBS S3D missiles was deactivated by President Jacques Chirac in February 1996.