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.

Eighty years ago, on Aug. 6, 1945, the United States dropped the first of two atomic bombs on Japan to force the unconditional surrender that ended World War II. The fearsome weapons were created by ...