A missile launch facility, also known as an underground missile silo, launch facility (LF), or nuclear silo, is a vertical cylindrical structure constructed underground, for the storage and launching of intercontinental ballistic missiles (ICBMs), intermediate-range ballistic missiles (IRBMs), medium-range ballistic missiles (MRBMs). Similar facilities can be used for anti-ballistic missiles (ABMs).
The structures typically have the missile some distance below ground, protected by a large "blast door" on top. They are usually connected, physically and/or electronically, to a missile launch control center.
With the introduction of the Soviet UR-100 and the U.S. Titan II missile series, underground silos changed in the 1960s. Both missile series introduced the use of hypergolic propellant, which could be stored in the missiles, allowing for rapid launches. Both countries' liquid-fueled missile systems were moved into underground silos. The introduction of solid fuel systems, in the later 1960s, made the silo moving and launching even easier.[1]
The underground missile silo has remained the primary missile basing system and launch facility for land-based missiles since the 1960s. The increased accuracy of inertial guidance systems has rendered them somewhat more vulnerable than they were in the 1960s[citation needed].
Other than underground facilities, ballistic missiles can be launched from above-ground facilities, or can be launched from mobile platforms, e.g. transporter erector launchers, railcars, ballistic missile submarines or airplanes.