Weapons of Mass Destruction. Remember those?
Were they, or were they not in Iraq? It didn't matter. Even without proof, the US went in there and turned the country upside down. When someone uses a biological weapon on planet Earth, the US military will track you down. If you use it on your own people, you will probably try to use it in Times Square eventually.
The case can be made that the Iraqi situation was political..oil, carryover from 1992, etc. But in Syria, there is no doubt the current regime used chemical bombs. The NSA has satellite and video proof. So get ready.
From Wonkblog this a.m.: