If Assad decides to go out with a bang, you would not believe how many cities he could shower with Chemical WMD and Biological WMD. The most advanced WMD in those categories on the planet right now. The Middle East region would be devastated with thousands dead.
Of course he’d still have to be north of room temp to order an attack on anyone.A more likely scenario iare his minions running for the exits and taking whatever they can as barter for their lives. This is how WMDs are likely to get into the hands of very bad people I thought the commies in Russia might do this with nukes but I guess Gorby and Yeltsin had the KGB keep a lid on. But getting out some canisters or arty shells of Sarin A&B is easy. These may not rain on Israel but may wind up in Times Square.