Regarding chemical attacks in Syria (as opposed to a different tactic), ask this question:
Cui bono? (who benefits)
Then proceed from that point on.
Who benefits? Well, I’ve thought about it and one side I see who doesn’t benefit, at all, is Assad? Why would he do this? It wasn’t a military tactic because it was of small effect, killing 45 and maybe killing 100 on a good day. It accomplished nothing in the visible scheme of things but it escalated the stakes and intensity a million times. And whoever did it knew it would escalate things - that’s why they did it. I can think of no reason anyone would do it other than to accomplish that objective. Assad seemed to have won it for now even if he does have new “partner” in the Russians. Why would he want to reshuffle the deck? Who benefits?
To win a war, to really win, you must break the will of your enemy. What would break them more than to know that assad, with putin’s help, could use chemical weapons with impunity? He did the calculations and decided he benefited. Meanwhile, his champion and patron, tell the lies that many swallow whole cloth, their reflex anti-Americanism making them vulnerable to the lies of a KGB thug.