Kinsman: Would establishing that Syria has used chemical weapons be enough trigger international intervention?

The reasons international intervention has so far been limited to support for the rebels (in the U.S. case, short of arming them) are that a) Russia and China and others less important oppose direct international intervention, thereby denying UN legitimization; b) the military challenges of doing in Syria what was done for Libya are very much more daunting, and the will in the U.S. and elsewhere is absent; and c) there is an ominous unpredictability of outcome if Assad is thrown out by foreigners (and even if he falls to insiders).

Would the use of chemical weapons change these three factors? Would it need to go beyond the apparent very limited uses thus far? After all, Assad has already killed tens of thousands of his citizens. What using WMD on his own citizens would do is make any kind of end-game exit strategy for Assad absolutely non-negotiable. By definition, chemical weapons represent a Hague offence even non-signatories of the ICC would have to respect, though Iran would stay solid presumably. International solidarity against him would tighten in lots of ways. Despite news reports Assad thinks he can hang on to power because the non-Sunnis in Syria look in growing fear to him for protection, the use of chemicals would hasten his inevitable fall. Presumably he gets that.