I don't believe any Sarin was used. But if it were, the more important question would be "where did it come from?".
Because Sarin has a shelf life of five years max under ideal storage conditions, Sarin would have had to have been manufactured since 2012. If so, where, and by whom?
My belief is that there was no chemical bombing, and that if gas were created, it was homemade cleaning chemical chlorine gas, delivered by mixing it in a open barrel for the wind to disperse.
In the western world, any community swimming pool has more than enough chemical potential stored to kill 1000 people. Even Goober and Gomer could make it work.
Phosgene gas?
There are a large number of scientists in the Middle East with the knowledge to manufacture chemical and biological weapons. Iraq had a few dozen mobile labs that were moved to Syria in the late 90s. A good friend and retired bioweaponeer made 39 trips to Iraq as part of the UN inspection team. Since this same team had an Iraqi mole in their midst, these labs were always a step ahead of discovery, and being mobile were moved to Syria, but the evidence was there according to the Col. The old media lied. The Col spoke the truth.
I tend to agree with you. There are three mystery parts to this story.
1. Sarin, at your very best shelf life is five years (it needs to be made with that intent, and stored in the right temperature). At the end of the spectrum, you make the stuff and have to use it within four weeks (it loses it potency then). If I go with this usage, then I’m inclined to believe they were within a month or two of the expiration date, and just made a spur of the moment decision to use it before it was useless.
2. The Russians. Why would then bother telling the Russians? I think the Russians were left totally out of the picture.
3. The vehicle of use? I would assume that the US monitors their airspace, and knew that there was only one single fighter that was in the region at the time....a Fitter, and it came from the base bombed. If it’d been an artillery shell....totally different scenario. But they have some witnesses saying the gas came from bomb that came out of the sky.
My observation is that Assad hasn’t shown brilliance as a leader and this might be just another example of poor leadership.