Peacekeeper ICBM at launch

Through much of the second half of the 20th century, the U.S. and the Soviet Union were mortal enemies engaged in a tense and dangerous stand-off. They hurled rhetoric in government chambers and over the airwaves, sent spies and spy planes into each other's territory, fought proxy wars, and most ominously, built sprawling nuclear arsenals with the capacity to destroy the other many times over.

At the heart of that Cold War policy of "mutually assured destruction" were the two countries' arrays of ICBMs, or intercontinental ballistic missiles, like the 1980s-era Peacekeeper seen here. Loaded with one or more nuclear warheads, they stood ready for a call to battle that, fortunately, never came. The first of the U.S. Air Force's operational ICBMs, the Atlas D, went on alert 50 years ago this month, on October 31, 1959--aptly enough, that is, on Halloween.