An artillery shell consists of a warhead, a propellent charge, and a primer of some kind. The warhead for a chemical weapon is a different one than the one for HE. I am going by the reports that the stockpile of warheads found were for chemical munitions.

And the comments about WMD by brucie are still valid- The US defined the use of chemical OR biological agents to be equivalent to the use of nuclear weapons in a battle environment. This was a deterrent against Soviet forces using chemical or biological weapons, when OUR stockpile of WMD consists mostly of nuclear devices.

"The use of WMDs in a tactical situation opens a facet of warfare that Iraq was not prepared for. US policy has been very clear for decades (ever since MAD): use them on us and the wrath of Shiva will fall on you, because we will use them back. "

A WMD is a WMD is a WMD.