FP: Two previous administrations have reportedly considered this course of action and dismissed it. Why did Trump act now?
DP: The reasoning seems to be to show in the most significant way possible that the U.S. is just not going to allow the continued violence—the rocketing of our bases, the killing of an American contractor, the attacks on shipping, on unarmed drones—without a very significant response.
Many people had rightly questioned whether American deterrence had eroded somewhat because of the relatively insignificant responses to the earlier actions. This clearly was of vastly greater importance. Of course it also, per the Defense Department statement, was a defensive action given the reported planning and contingencies that Suleimani was going to Iraq to discuss and presumably approve.
This was in response to the killing of an American contractor, the wounding of American forces, and just a sense of how this could go downhill from here if the Iranians don’t realize that this cannot continue.