President Barack Obama told the world on Friday in Hiroshima that the American decision to drop nuclear bombs on Japan in 1945 arose from humanity’s worst instincts, including “nationalist fervor or religious zeal.” The war that ended in Hiroshima and Nagasaki, he said, “grew out of the same base instinct for domination or conquest that had caused conflicts among the simplest tribes, an old pattern amplified by new capabilities and without new constraints.” The speech — delivered on the eve of Memorial Day weekend — was billed by the White House as anything but an apology, but Obama’s words betrayed...