Bush declares himself deliberately agnostic as to why these Iranian munitions are in Iraq and who the Iranians may be giving them to. This is, however, the central issue at hand: not whether the al Quds force is operating with or without the approval of the Iranian government, but whether the al Quds force itself is actually responsible for arming fighters using the weapons against American soldiers and marines.
At stake is whether or not the Iranian government is pursuing what amounts to an act of war against U.S. troops.
Any number of alternative explanations are possible: renegade Qods Forces could be trying to make money on the lucrative Iraqi black market for weapons. Iran could simply be arming its Shiite proxies in the civil war as opposed to seeking attacks on U.S. forces. And those proxies could in turn be unloading some of the weapons on the very active black market. (Remember, some of them were discovered in December at a compound belonging to U.S. "partner" SCIRI.) An element of the Qods Forces could be attempting to attack U.S. forces without the knowledge of their leadership. And so on. These are contending theories that require additional information to be compelling. And there should be some explanation of why most of the deaths of US forces from these IEDs are coming from Sunni insurgents who are opposed to the people Iran supports -- a fact that some believe points to the black market.
Three things are significant about this. First, it's deliberately an argument by innuendo. Without specifying even what the U.S. is alleging about Iran, viewers (and journalists) are invited to draw their own inferences -- inferences understandably likely to be alarming. Second, we've been here before. It's exactly the sort of innuendo put forward by the administration before the Iraq war, when officials endlessly told us that Abu Musab al-Zarqawi was "in Baghdad" -- and so we were to believe that al-Qaeda and Saddam Hussein had the sort of operational relationship they never had.
Finally, these two points represent something of a gauntlet to administration critics. It becomes incumbent on them to make the case that the Iranian government isn't involved in attacks on U.S. forces. Bush, on the other hand, takes the posture that he won't wait for dangerous threats to gather until they're perfectly clear. It's an emotionally compelling stance. Unfortunately, we've seen its effects in Iraq for the past four years.