If you just blow them up with conventional explosives, they have a tendancy to become dispersed, and many of the known stockpiles are near civilian population centers. I think it takes something like 2,100 degrees F to incinerate the stuff. You might be able to to it with FAE, but the material would have to be exposed first, and FAE is anything but a "precision" weapon, it would damn near caus as many civilian casualties as just blowing up the bunkers.

All this assumes we are able to actually determine that it was Assayd's forces that actually used the things in the first place when it is well known that both sides in the conflict have them.

It would almost be more resonable to tell everyone to get out of the city they were used at by a certain date, and then just bomb it into COMPLETE rubble, than to try and pick a side that is "to blame."