The French military wasted no time bombing Syria in retaliation for the attacks, though it is not known where exactly the attackers were from. Thousands of ISIS fighters in Syria are not Syrian, but came to Syria to overthrow the Assad government from a number of foreign countries -- including from France and the US. 

Ironically, the overthrow of Assad has also been the goal of both the US and France since at least 2011.

Because the US and its allies are essentially on the same side as ISIS and other groups – seeking the overthrow of Assad – many of the weapons they have sent to the more "moderate" factions also seeking Assad's ouster have ended up in the hands of radicals. Moderate groups have joined more radical factions over and over, taking their US-provided training and weapons with them. Other moderate groups have been captured or killed, their US-provided weapons also going to the radicals. Thus the more radical factions have become better equipped and better trained, while occasionally being attacked by US or allied planes. 

Does anyone not believe this is a recipe for the kind of disaster we have now seen in Paris? The French in particular have been very active in arming even the more radical groups in Syria, as they push for more political influence in the region. Why do they still refuse to believe in the concept of blowback? Is it because the explanation that, "they hate us because we are free," makes it easier to escalate abroad and crack down at home?