Late 2017 Turkey signs 2,5 bln. USD contract with Russia for S400 defense systems. Western alliance attacks Syria with 105 missiles. Moscow claims that 75 missiles where taken down and Syria used old S200 systems among others to repell the attack. Turkey president congratulates Western alliance with the attack.
Well, I don't know, but considering all the circumstances to me it looks like promotion of a product through showcasing it in battle conditions.
This leads me to a conclusion that chemical attack was staged to get needed response from Western world.
RE: DTube - BREAKING- Syria Under Attack!1 US/France/UK Strike - Russia Threatens Retaliation - PFT Live