There is a fascinating interactive graphic that shows the military relationship between many of the actors interested in Syria. While I don't know that much about the overall situation in Syria, I do know, it's complicated. I do think the domestic rhetoric is largely ignorant of the region's history and the various narratives that are at play. In other words, people talking about what should or should not be done in Syria, don't know what they are talking about - generally. Check out this interactive to get a little better feel for the military considerations that all actors are facing.
Connecting Syria's allies and enemies - Interactive - Al Jazeera English