Nuclear missile silo test site. Aerial photograph of an underground nuclear missile silo survivability test site. This site is used to test whether US nuclear missiles (fired from underground silos) would survive an attack intended to destroy them. The missiles (intercontinental ballistic missiles, ICBMs) are some distance below the surface, protected by blast doors. The silos are heavily reinforced-steel and concrete underground structures that in addition were often hardened to withstand huge blast pressures. This site is near Yuma, Arizona, USA. Photographed on 10 April 1986.