what do you mean when you say the fsa morphed into isis? i remember when fsa was having trouble with aq infiltration and the independent action of aq brigades. were these brigades the seed of isis? it kinda seems isis emerged as a distinct entity from fsa, rather than that fsa morphed into isis. like a wasp from a caterpillar. maybe i am wrong. but that is my sense of what occurred. isis doesn't look like a syrian movement to me. it isn't about nationalism. it's about fundamentalism and an islamic caliphate.
no independent knowledge, but i have read that the best trained of the isis people are chechens who have been fighting for years - in chechnya, afghanistan, syria, iraq. it kinda seems that wherever there is an uprising, fundamentalists and aq-affiliated people show up. many of them have become fairly expert at fighting over time.
i think the fsa was a ramshackle group of actual syrians. but these foreign fighters are a quite different thing. and they are one reason the us was loathe to get involved in syria. distinguishing freedom fighters from fundamentalists is not easy.
funny how everyone has complained about the us not engaging in syria and yet still you assume they are somehow responsible for isis. there is no plausible link that i have seen between the us and isis. isis isn't a creature of western manipulation. it's a movement of nasty fundamentalists that has been gradually gathering strength. but as it crystallises into a territorial power, it has also become vulnerable.
remember what happened to the taliban when it held territory?