Where do you even draw the line? There is no 'terrorist' faction, anyway, but a whole host of bad guys.
There are local Baathist moneymen/faciliators
Foriegn fighters from Syria and other nations
Iranian intelligence agents/IRGC commandos
Locals hired to plant mines, act as spies, or snipe
Criminal organizations
And a random assortment of malcontents and uncivilized jerks. None of these guys carry I.D. cards that say what is running through their heads when they decide to shoot at Americans. How are a pack of British MDs going to figure out who's a 'civilian' and who's not?
I personally think the more terrorists we kill the better.
Al-Jazeera