|Use 'em or lose 'em?|
First, a clarification in terminology. Chemical weapons are NOT WMD. As typically visualized, weapons of mass destruction are strategic weapons, most useful as deterrents to aggression rather than tactical or battlefield employment. The category specifically covers nuclear weapons, and can, under some circumstances, include some types of biological weapons. You can envision nuclear weapons destroying entire cities, and biological "superbugs" decimating populations over a large area - hence the concept of 'mass destruction' - but you cannot envision anything of the sort with chemical weapons. They are specifically battlefield weapons, useful to whatever extent they are useful in stopping large infantry units, or, more commonly in recent years, in putting down revolts by killing very large numbers of the rebellious population. You'll recall that Saddam Hussein used nerve agents and Mustard gas to kill 10,000 Kurds at Halabja in 1988. Chemical weapons are often categorized with their nuclear and biological cousins (NBC) as unconventional weapons, and later, when the concept of WMDs and terrorism was seized upon by the vile and corrupt GW Bush administration to justify initiating aggressive wars, it was convenient to include chemical weapons in the WMD category - many nations lack any significant nuclear weapons program, but virtually all have some chemical weapons inventory. Thus the US could use this excuse to justify an aggressive and belligerent posture against any nation they chose.
Syria's chemical weapons have been in the news lately because there have been reports that the Syrian Army along with Ba'ath party loyalists have been moving them out of their long-term storage facilities. There are three possible reasons they might do this.
1. To retain control of their most dangerous weapons in case of foreign invasion
2. To prevent them from falling into the hands of the rebels and finding themselves subject to threats or even the realities of chemical attacks
3. In preparation to deploy chemical attacks against the rebels, as other mid-eastern despots have done in the past
The effects of these types of weapons are so awful, and so indiscriminate, that it seems likely that any significant release would result in prompt international intervention. There is quite a lot of discussion that the US, in partnership with Israel, or perhaps Jordan, might launch an operation to attempt to secure al-Assad's chemical stocks, but this seems more fantasy that reality. The weapons are dispersed, and are in the form of aerial bombs, artillery shells and even 122mm Katayusha/MLRS type rocket warheads, which are small enough to be carried by an individual. So the fate of these weapons is very much dependent upon the way the conflict ends. If Syria sees a period of chaos, all out war without central governance, it is certain that some portion of the weapons, particularly the nerve agents, will be lost to militias, political organizations and international criminals and traffickers. And one would expect to see them used in some of the many regional sectarian and political conflicts.
On the other hand, to be fair there have been a large number of MANPADS surface-to-air missiles systems available for many years, and in the last ten years we have seen only one - failed - terrorist attack using them: The 2002 Mombasa attack. However, chemical weapons are a different category, more broadly useful and after nearly 20 years we are still talking about the Aum Shinrikyo Sarin gas attacks in Tokyo.
Whoever it is that ends up in the political leadership in Syria will have plenty of incentive to locate and control the chemical weapons. No matter whether they bear any responsibility, a massacre of civilians using Syrian chemical weapons will paint that ancient nation as a a hotbed of terrorism and hatred for a generation, and in the aftermath of such an attack Syria might face brutal retaliation. But ultimately, this genie is out of the bottle. It's unlikely that the collapsing regime will be focused on, or even capable of, controlling all their disbursed weapons depots. As we've seen in other recent revolts, the military stocks of the erstwhile leadership have been looted by everyone with a passing interest. One has to conclude, at this point, that these stocks will be around to haunt us for a long time to come.