He has to do something now, he backed himself into a corner with the "red line" comments. Hopefully it is limited to some cruise missile strikes
Sadly, that red line comment could turn out to be a very expensive mistake. The gas attack on the 21st (whoever's responsible) appears to have been a deliberate provocation specifically designed to drag the US into the war - ironically, on what is seen in the region as the side of al Qaeda. It cannot be coincidence that the attack happened as the UN inspectors arrived in country and a mere 15 minutes from their hotel.
On the face of it, that would seem to lend credence to the Russian claim that it was the rebels what done it however, you have to remember that Assad's main supporter in the region is Iran.
The Iranians have enjoyed a decade fighting and winning a proxy war in Iraq against their greatest enemies, the Saudis and the US. That war recently ended and doubtless, elements in Iran would like nothing better than another crack at their long time foes, particularly when proxy war has proved so successful and cost so little thus far.
Another of Assad's main backers is a Russia run by a cold war relic with a cold war hatred of the west and doubtless some very hard feelings about the Russian experience in Afghanistan and the US's involvement in that: I'm guessing he enjoyed seeing the US getting it's ass kicked in two countries over the last decade and that he, too wouldn't be averse to a little more of the same ..
Then, as I've said elsewhere, the Syrian war is between two western foes: Assad and al Qaeda. The western Machiavellian calculation has to be: long may it continue. Assad is currently winning - a bit of indirect help for the rebels would be quite timely.
.. so basically, what I'm saying is, good luck limiting western involvement to a few missiles
