i don't know if knee jerk is the right metaphor. seems to me he painted himself into a corner and figured that was the only way out. Then Parliament spoke - effectively forcing him consult with congress - and the rest is history.
The surprise (to all including putin imo) is that syria would come so far so fast.
Russia is as, or perhaps more, vested in CQ disarmament of anything south of the border as the US is. Plenty of goofballs would like to gas the Moscow subways, and it is easier to get from a broken syria to moscow than it is to get to NY.
Sp Russia gets to reassert world stage relevance (and secure a real threat), Assad gets to sign a piece of paper (which makes him the de facto government) BO manages to whitewash his red lines, and Syria continues on its soul searching path of settling on nation of some sort.
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