The same old stuff that’s been entombed there by the U.S. military for over a decade. Little if any of it is viable for any current warfare purpose. I hope I do not turn out to be wrong. If so, how is it conceivable that it existed right under the nose of U.S. forces for all those years?
Considering Iraq was making binary mustard and nerve agents, I hope you are right. They had considerable stock piles of mustard and sarin that were produced after the war with Iran. Binary configurations have a pretty long shelf like, far longer than unitary. Iraq spent considerable time and effort refining both. Most were placed in artillery shells, perfect for IED use and easily transported.
During their war with Iran, Iraq was only producing short lived, unitary nerve agents and mustard. It is highly unlikely these are left overs as they would have been destroyed due to their short effective lifespan.
Even if they have 50% potency they could scare an urban center into surrender. It wouldn’t take much. They could use it on the Kurds, the Iranians, Jourdan, Iraq. As a weapon of terror—they have greater value than as a military weapon. They IS are fighting a political terror war (the same way Gengis Khan waged and Tamurlane and the Japanese in China).
You mean warfare like "civilized" people engage in warfare, force on force, uniformed military against uniformed military, like we did in The Great War? How very 19th century mindset of you! (Still the mindset in the early 20th century)...
Or do you mean warfare like our enemies engage in, poisoning subway stations, burning down churches full of parishioners, invading schools and shooting, hacking and blowing up little girls?
That kind of warfare?