"An explosive containing sarin nerve gas was discovered by American troops in Baghdad and detonated," the Times reports. "It was the first sarin shell the American military has found since the invasion of Iraq last year, the spokesman, Brig. Gen. Mark Kimmitt, said in a televised news conference.

The explosive, a 155 millimeter artillery round, had been rigged as a roadside bomb, the general said. It was detonated before it could be defused, producing "a very small dispersal" of the gas, he said.

Two members of a bomb squad were treated for minor exposure, and the sarin did not present a threat to the surrounding neighborhood, the spokesman said.

The incident occurred "a couple days ago," he added.

General Kimmitt said American officials believe the weapon came from the stockpiele of the regime of Saddam Hussein. Mr. Hussein had declared all such rounds destroyed before the 1991 Gulf War.

The bomb was a "binary chemical projectile" with two chambers each containing a distinct chemical. When the projectile is fitted into an artillery round and fired, the rotation of the round causes the wall between the chambers to break, thereby blending the two chemicals. On impact with the target, the shell explodes, releasing the sarin.

But the explosive discovered last week was not launched as an artillery round, so only a small amount of the two chemicals mixed together, General Kimmitt said. It was not known whether whoever rigged the bomb knew of the presence of sarin in the explosive.

THERE'S MORE: "While deadly, sarin gas is not likely to be effective when used in this manner," explains Lt. Smash. "Chemical artillery shells are designed to "pop" rather than explode, and are generally fused to detonate well above ground level for better dispersal. Any chemical attack via artillery would have to use several shells over a wide area to be effective.

So either this is a false alarm, or whoever planted this explosive:

- Didn't know that it was a chemical weapon, or

- Doesn't know how to properly employ such a chemical weapon, or

- Intended to terrorize the Coalition, rather than cause significant damage.

Given that the proven existence of chemical weapons in Saddam's arsenal represents a major propaganda victory for the Coalition, I find the third possibility to be highly unlikely. Of the remaining two possibilities, I'm more inclined to believe that the bombers weren't familiar with the difference between chemical and conventional artillery shells, and assumed they had the latter.

AND MORE: "It appears the insurgents didn't even know they had a chemical round," former weapons inspector David Kay tells the AP.

While Saturday's explosion does demonstrate that Saddam hadn't complied fully with U.N. resolutions, Kay notes, "It doesn't strike me as a big deal."