The actual decision to drop the bomb was not nearly as casual as “a simple yes.” Critics of the decision to use the “special bomb” in 1945 are judging men born in the 19th century by the standards of the 21st. Had Truman and his commanders shrunk from doing everything possible to force the war to its end, the American people would never have forgiven them. This judgment no doubt mattered more to these leaders than the disapproval of academic historians a half century later, and rightly so.

Nuclear arms are hideous, immoral weapons whose existence continues to threaten our civilization. To say, however, that Harry Truman should have sacrificed hundreds of thousands of American lives because of what happened in the nuclear arms race decades later is not only ahistorical, it is moral arrogance enabled from the safe distance provided by time and victory.

Tom Nichols is Professor of National Security Affairs at the Naval War College and an adjunct at the Harvard Extension School.