What makes you think this is the "spark"?
If you look at large conflicts historically, many small conflicts run up to the larger conflict. I'd say we've met that bar for many years. If anything, this is a run away train that's shootings sparks every which way at this point.
+1
Eventually, one of those sparks in going to fall into a crater filled with TNT. Not sure Syria is that crater, but the world seems to be growing weary of getting burned by reckless sparks.