Among several broadly held misconceptions about Iran is that to get Iranians to make concessions we want them to make at the negotiating table the United States must credibly threaten to inflict dire harm on them—specifically, with military force—if they do not make the concessions. Some in the United States (and some in Israel) who are especially keen on promoting this notion would welcome a war. If war preparations and brinksmanship used to communicate such a threat lead the two nations to stumble into an accidental war—and there is a real danger they might—so much the better from their point of view. But the belief in saber-rattling as an aid to gaining an agreement in the negotiations over Iran's nuclear program extends to many who actually want an agreement and are not seeking a war. We have heard more about this lately in connection with Chuck Hagel's nomination to be secretary of defense. People ask whether this nominee, who has evinced an appreciation of the huge downsides of a war with Iran, would be able to rattle the saber as convincingly as the same people think a secretary of defense ought to rattle it.