The 80th anniversary of the atomic bombing of Hiroshima and Nagasaki is this week. It was the only time nuclear warheads were used during war. Here’s a look at the history and current U.S. stockpile.

In the wake of the blast, these eerie shadows were left etched into surfaces across the city—almost like a photo negative of those who were lost. When the atomic bomb detonated over Hiroshima, it left ...