The American and Israeli bombing of Iran failed to provoke either a popular uprising against the regime in Tehran or its capitulation, however painfully slow Mr. Trump and his advisers have been to acknowledge that. Instead, Iran discovered its ability to shut down the vital passageway of the Strait of Hormuz and send the global economy into chaos.

There are now only two outcomes to the conflict: either the kind of wholesale destruction of Iran that Mr. Trump posited, or a settlement that will leave the government intact and empowered, and a blustering American president humiliated.

The first option is increasingly remote. By publicly threatening the commission of war crimes on an enormous scale, Mr. Trump has given both his domestic and foreign opponents time to marshal resistance. As for the latter and more likely outcome, this was predictable, if only the president and his administration had bothered to take note of a new feature of modern warfare, a feature that can be boiled down to a single word: drones.