Syria has had chemical weapons for decades, long before the 2003 invasion of Iraq.
Chemical weapons are a poor man's nukes, and is their counter balance to Israel's nuclear arsenal.
And it is perfectly plausible that the Syrian opposition grabbed some of these weapons in a successful raid.
It would be hard for Assad to make that public....it would be tantamount to the poor schmuck who calls 911 to report that somebody stole his marijuana.
That said, the Turkish authorities just captured a couple canisters of sarin gas in somebody's apartment....a rebel's apartment.
Ambassador Stevens met with the Turkish Ambassador that fateful night, just moments before the attack commenced. They were going to ship weapons and arms and parts through Turkey for Assad's opposition.
Two plus two still equals four.