For about 20 years during the Cold War with the Soviet Union the peace policy called "mutually assured destruction" was maintained on the USA side by 54 Titan II missiles scattered around the US tipped with 9 Megaton nuclear warheads.

9 megatons is the largest warhead ever put into service during the Cold War and would have left a crater 39 miles in diameter where a target used to be if ever fired off. The Titan II could deliver a warhead anywhere on Earth.

The theory of "mutually assured destruction" was that both the US and the Soviet Union would never attack the other because each country maintained enough survivable nuclear weapons that they could totally destroy the other even if they were the victim of a surprise attack.

There were 18 missile silos scattered around Tucson, Arizona. I remember them well because they were fully operational when I was studying physics at the University of Arizona.

This is one of those silos. It was converted to a museum after all the Titan IIs were decommissioned as part of strategic arms limitation treaties(SALT) worked out between the United States and the old Soviet Union.
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