There exist an interesting series of pictures of technicals evidently used for laying down gas. A howitzer equipped with something like a gas-protected sort of tent.
Used by Iran against the North. We have the shots, but they’re virtually unknown.
How fast does sarin act? Is it a thing where the person who disperses it would have to be protected or else they would die before they could finish the job - like if they were in a crop-duster? How likely is it that if the rebels used sarin they had delivery systems from somebody higher, like Iran or (gag) Obama?