You would have to be a fool to believe that Assad has successfully waged war against insurgents and terrorists for roughly six years, won much of their lost territory back, while carefully playing a dangerous political chess game on the world stage to thwart foreign military intervention targeting its own national forces, to then now, six years into a successful campaign on all front, use WMD's.
Also, lets now forget that all parties reached an agreement in late 2013 for the chemical weapon disarmament of Syria.
It is beyond absurd, and at this time, after going round and round with friend on the subject, do not have the energy to give this the post it deserves. More to come later.
More (and much more beyond these) on Syria: