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.

The US strike on Iranian nuclear sites — dubbed “Operation Midnight Hammer” — was the biggest ever attack by B-2 Spirit stealth bombers, and the longest flight the aircraft have made since 2001. It ...