It may seem bizarre and even redundant, but the semi-truck barrier serves as the very last safety precaution against an accidental launch.

The U.S. Air Force’s latest Minuteman III intercontinental ballistic missile system test at Minot Air Force Base, North Dakota, included a semi-truck parked over the silo, an added precaution to absolutely rule out an accidental launch. This seemingly crude measure is a routine part of these ICBM tests, codenamed Giant Pace, which evaluates the reliability of the land-based leg of the U.S. nuclear triad.

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In October 1984, Air Force officials parked an armored car on top of a Minuteman III silo at F. E. Warren Air Force Base in Wyoming after a computer malfunction lit up a warning light indicating that the missile was about to launch itself. “Security police did respond with a vehicle that was parked on the missile silo,” Major Fred Harrop, a Strategic Air Command spokesperson, told The Washington Post in 1987 after details of the incident emerged.

moznoze sme boli blizsie atomovej vojne viackrat, ako je vseobecne zname...

src: https://www.thedrive.com/the-war-zone/40411/the-air-force-parks-trucks-over-icbm-silos-during-non-launch-tests-just-in-case