Obama believes attacking Syria will send a message. He's correct, it will, but the message will not be what he thinks. Rather than a forceful show of strength, the world will view it in these terms:
there they go again, doing something they would never want done to them, and demonstrating that they alone think they can decide what deaths constitute a moral obscenity and what constitute mere unfortunate collateral damage.
The Syrian situation exists purely because the Obama foreign policy has been weak. As a result, it has fostered situations which allow tyrannical leaders to be overthrown, with tacit approval of the US government, without any support or plan for providing material support afterward.
Each of these situations has become chaotic - which is precisely what should have been expected, since the region in question has never been completely stable and any hint of stability had previously been provided by despotic regimes. When these despotic regimes have faced a populace encouraged to stand up, they have fallen (as expected), and reverted to anarchy.
Obama is faced with a situation which he didn't plan for, but should have. Increased anarchy in a region he hoped he'd guide gently toward democracy. He has learned you can't reason with mobs or tyrants. And now he's learned what every other leader in the world knows - if you want to deal with tyrants, you have to do so from a position of strength.
But he has squandered our strength.
Now he needs to regain it and lacks the ability to do so. He is hoping a show of military force will help. He is wrong. He can only make things worse now. Best to back off, disengage, and let the chips fall where they may.
