It might be wise to remember that Assad isn't the only WMD owner in the region:
Turkish security forces found a 2kg cylinder with sarin gas after searching the homes of Syrian militants from the Al-Qaeda linked Al-Nusra Front who were previously detained, Turkish media reports. The gas was reportedly going to be used in a bomb.
The sarin gas was found in the homes of suspected Syrian Islamists detained in the southern provinces of Adana and Mersia following a search by Turkish police on Wednesday, reports say. The gas was allegedly going to be used to carry out an attack in the southern Turkish city of Adana.
On Monday, Turkish special anti-terror forces arrested 12 suspected members of the Al-Nusra Front, the Al-Qaeda affiliated group which has been dubbed "the most aggressive and successful arm” of the Syrian rebels. The group was designated a terrorist organization by the United States in December.
http://rt.com/news/sarin-gas-turkey-al-nusra-021/
United Nations human rights investigators have said that they have gathered testimony from outside Syria suggesting that the rebels, and not Bashar Assad's regime, may have used chemical weapons.
"Our investigators have been in neighboring countries interviewing victims, doctors and field hospitals and, according to their report of last week which I have seen, there are strong, concrete suspicions, but not yet incontrovertible proof of the use of sarin gas, from the way the victims were treated, "Carla Del Ponte, a member of the UN independent commission of inquiry on Syria, told Swiss-Italian television. "This was use on the part of the opposition, the rebels, not by the government authorities," she added.
http://www.clarionproject.org/...sed-chemical-weapons
It is possible that a conventional weapon found a WMD stash; it has happened before:
https://en.wikipedia.org/wiki/Air_Raid_on_Bari