The US has already told Saudi Arabia, Iraq, Lebanon, and Jordan that it would assist those those countries if chemical weapons were found crossing their borders.
Russia, Syria’s strongest ally and a longtime arms supplier, knows well that the weapons are a big problem, one that may blow back on Russia itself if they go missing. Their use by Assad forces would constitute a war crime, and would likely push the international community to approve a quick invasion of Syria.
Use of chemical weapons by a Baathist minority government against the ruler's own people would be a war crime justifying a "quick invasion" of Syria?
Fancy that.
Now that I think about it, we even mentioned that back in 2002:
... the current Iraqi regime has demonstrated its capability and willingness to use weapons of mass destruction against other nations and its own people ...
Gosh. What's different now?