Here we go, following me to yet another thread for a quick troll.
If I recall, the Douuma chemical attack, if it ever happened, was attributed to Assad, but by the same people that told us all about Iraq's WMD, witness statements were all from people fighting Assad, and lots of people disputed it ever happened with a lot of sound evidence to show their point. They also noted lots of evidence to show the rebels and ISIS had, and used, chemical weapons. The US told us these were the ones Iraq managed to get to Syria before the weapons inspectors found them.
Assad is a big enough bastard and there's plenty of clear, undisputed evidence for that, without believing dodgy stories from the "Iraq has WMD" people.
Now please fuck off and stalk someone else.