In the U.S. and Europe, much of the mainstream media has swallowed a narrative about Donald Trump and Iran. While Iran is an aggressive authoritarian state, the story goes, it is nonetheless a victim of American belligerence. Tehran was adhering to the Joint Comprehensive Plan of Action, negotiated by the Obama administration, when the truculent Mr. Trump abruptly abandoned the accord. For more than a year, according to the narrative, the mullahs have shown patience by continuing to abide by the agreement, even with the resurrection of punishing American sanctions.

Iranian...