It would have made strategic sense. It was certainly reasonable to expect that a CBW attack, if it was ever going to happen, would have happened when U.S. forces reached the outskirts of Baghdad. After all, what was the point of positioning the Republican Guards there if not to create chemical-biological killing fields? Otherwise, digging in around Kut and Karbala would not differ dramatically from "hunkering down" in Kuwait, as in the last war.

It would have been consistent with what we know about Iraqi doctrine. Former arms inspector Charles Duelfer has reported that in 1995, the Iraqis explained to UNSCOM that they considered chemical weapons to have been the "silver bullet" that saved Saddam twice: first by stopping the Iranians during the Fao campaign, and later by deterring an American march on Baghdad in 1991. Much more recently, the Iraqis have dropped hints that the U.S. could expect the same approach to regime preservation. Following that logic, this would have been the right time and the right place.

There is circumstantial evidence that the Guards were preparing for a CBW attack. Recent reports (here's one) claim that dead Iraqi soldiers spotted along the road to Baghdad were carrying their gas masks.

This mystery could be explained by an early and persistent breakdown in command and control. It may be that a planned CBW attack failed to come to pass because those responsible for conducting it never received final authorization, were disorganized, were in the wrong place, could not communicate, had been killed, etc., etc. When we compare this puzzling absence to other seemingly inexplicable Iraqi failures -- to torch more than a handful of oil wells, to succeed at blowing up any bridges or dams, to launch a significant retaliatory missile campaign, or to put any planes in the air -- it all looks of a piece.

(An aside. Iraq's apparent inability to destroy bridges is especially damning, since heavy U.S. ground forces have been able to cross the Tigris and Euphrates without any great complications or delays. This may mark one of the low points in the history of defensive warfare. I imagine American combat engineers shaking their heads and tsk-tsk'ing as they check bridges captured either intact or with modest damage only.)

Still, it's too soon to be sanguine. There is another, more troubling explanation: Saddam may have reserved his arsenal of nasty stuff as a key piece of an infrastructure of revenge designed to deter his enemies, or at the very least to enhance his posthumous glory.

The idea of an undisclosed plan for vengeance from beyond the grave should bring to mind Dr. Strangelove's bewildered question to the Soviet ambassador: "Of course, the whole point of a Doomsday Machine is lost if you keep it a secret! Why didn't you tell the world?" But it also may be consistent with past behavior. During the last war, Saddam's Scud operators supposedly had orders to fire everything they had left at Israel in the event that the regime fell. In this scenario, shortly after the fall of Baghdad, Iraqi commanders will unleash their CBW at Israel (or at less appealing but more accessible targets) using any planes or missiles that can fly.

Whether Iraqi commanders would be able or willing to execute such a plan remains unknown. But there should be little doubt about Saddam's interest in the idea. In his most recent televised statements, the Iraqi dictator has signed off with variations on "Long live Palestine! Long live Iraq!" Keeping his history in mind, it should not be surprising if Israel turns out to be Saddam's target of choice for another sort of sign-off message entirely.