Although South Dakota’s Minuteman missiles now belong to history, the United States still has 400 Minutemans ready to launch from silos in North Dakota, Montana, Wyoming, Colorado and Nebraska. Each of the missiles is a Minuteman III — two generations advanced from the Minuteman I that was in the Lima-02 silo in 1964.

The Minuteman III fleet is just one part of the U.S. nuclear-weapons triad, which comprises 5,113 nuclear warheads in all, including some in storage and others that are deployed and ready for use from land, sea or air.

To opponents of nuclear armament, that’s a lot of accidents waiting to happen. The U.S. government has officially acknowledged 32 accidents involving nuclear weapons since the 1950s, while additional accidents, incidents, mishaps and close calls have been uncovered by journalists and activists.

And accidents continue to happen. In 2014, three airmen were conducting maintenance on a Minuteman III missile at a silo in Colorado when an accident caused $1.8 million worth of damage to the missile — roughly the same amount of damage, taking inflation into account, as the 1964 accident in South Dakota. The few known details of the 2014 accident were revealed only after persistent requests for information from The Associated Press.