Well, here I go with a big tin foil hat - 2nd time tonight:
The only possible reason I can see (not that I agree with it at all!) is that we use the chem attack as an excuse to hit Syria. Iran has said our hitting Syria will get them (Iran) further involved, which I assume means some sort of direct attacks on U.S. forces or allies, which then gives us the excuse to go after Iran’s nukes.
Under this scenario, the Obama Administration assumes Russia will stay out of it, at least in terms of direct action, but, as others have mentioned, this sort of supposedly controlled escalation is not how things usually transpire / unravel. This type of mindset, “controlled escalation” is exactly how libs think, when you look at how they think in a more general context.
Once again proving the validity of the Law Of Unintended Consequences.