The pregnant question regarding Syria is; “what happens the day after”. What happens the day after is contingent on the nature of the strike.
If the U.S. attack is the ‘message’ strike promoted by the administration leaving the Assad regime in power, albeit degraded, look for Assad to launch more attacks including chemical attacks. Keep in mind that the August 20 chemical attack occurred after the U.N. inspectors were on the ground. If in fact it was Assad who launched the attack it was a major ‘in your face’ massage from the regime. Assad is faced with a win or die scenario as are the Alawites and Christians in his coalition.
The neighborhood that was the focus of the attack has a, if not ‘the’ critical roadway in and out of Damascus. The Syrian Army has failed time and time again to regain control of this area from the Free Syrian Army. This roadway is not far from the airport where critical Russian and Iranian supplies arrive. For Assad to stay in power he has to regain this territory and WILL use gas to do it. The use of gas was a signal that the Syrian Army has been an abject failure, and to assume they will suddenly get a whole lot more effective is an unlikely assumption.
If the strike is ‘significant’ and sets the conditions for defeat of the Assad regime the stage is set for a continuation of the civil war, this time drawn on sectarian lines. Al Qaeda affiliates has taken ground in Syria, they won’t give it up to the Free Syrian Army and its affiliates.
There are by some accounts up to 1,200 different groups within the context of the opposition in Syria. The Jihadists are migrating into Syria from Lebanon, Iraq and our supposed ally Turkey. All turning a blind eye to the infusion of Jihadist fighters.
In terms of Syrian retaliation options, recent history says they will do little if anything. The Israeli strike on the Syrian nuclear facility drew no official response from Syria. It is also within the realm of possibility that Iran is, in light of the feckless Syrian Army, is reevaluating their support and whether or not to waste Hiz’bAllah in the effort. Iran is suffering economically and a longer term commitment to Syria may not be feasible.
Russia is a player and has a bloody history with Sunni extremists. Middle Eastern Sunnis know what Vlad has done to Chechen Sunnis. Students of the Middle East also know that despite the rhetoric Israel has been able to deal with Assad with little or no push back.
What we do know about the day after is that whichever way it goes American action or inaction will be blamed for whatever comes next. It will be blamed by an international community that has a voice but no spine.