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The cupola of an underground R-12U launching silo in Plokštinės missile base, Lithuania

A crew works on a Minuteman II in its silo.

A Peacekeeper MX launches from its silo

A missile silo is an underground vertical cylindrical container for the storage and launching of intercontinental ballistic missiles (ICBMs). They typically have the missile some distance under the surface, protected by a large "blast door" on top.

Until the 1960s ICBMs had been launched from surface bases. The Soviet Union used completely aboveground launchers similar to those found at a spaceport, which made them vulnerable to US bomber attack. The missile silo was first suggested in the 1950s in the United Kingdom as a suitable housing for Blue Streak missiles. Only one test missile silo was built in the UK at RAF Spadeadam and with the cancellation of the Blue Streak project, the UK ICBM nuclear missile capability was transferred in 1960 to submarines; however the idea of the underground rocket bunker was adopted by the USA.

The US Atlas missile used four basing schemes. The first were vertical, above ground launchers at Vandenberg AFB, CA. The second was stored horizontally in a warehouse- / shed- like structure with a retractable roof at Warren AFB, WY. The third was somewhat better protected, stored horizontally in a concrete building known as "coffins", then raised to the vertical shortly before launch. These rather poorly protected systems were a side effect of the cryogenic liquid fuels used, which required the missiles to stand empty and then be fueled immediately prior to launch. The fourth version of the Atlas ICBM (the Atlas F) were stored vertically in underground silos. The Atlas was fueled in the silo and then had to be raised to the surface for launch. It could not be launched from within the silo. The Titan I missile used a similar silo basing scheme to the Atlas F.

Things changed with the introduction of the US Titan II and the Soviet UR-100 missile series. Both used new liquid fuels that could be stored in the missiles, thereby allowing for rapid launch. Both systems were then moved to the silo system. The introduction of solid fuel systems in the later 1960s made this even easier.

The silo has remained the primary basing system for land based missiles since that time. However, the increased accuracy of inertial guidance systems has since rendered them somewhat less protected than they were in the 1960s. The US spent considerable effort in the 1970s and 1980s designing a replacement, but none of the complex systems were ever produced. The US, the USSR, and China all developed mobile ICBMs as well, but only the Soviet Union and China put them into production.

• Mobile Protective Shelters (MPS) plan, in which 200 Peacekeeper missiles would be shuttled around between 4 600 soft shelters.
• Midgetman missile
• One version of Topol-M
• DF-31 (CSS-9): a Chinese road mobile ICBM (China also two older mobile IRBMs)

Today much of the US arsenal has been placed on submarines (as SLBMs), while Russia has downsized their own force to a handful of mobile and silo-based weapons. China also has silo-based weapons, but is now concentrating development on expanding its submarine and road mobile weapon capability.

The increase in decommissioned missile silos has led governments to sell them to individuals, who then convert them to indisputably unique abodes.