External intervention in a civil war is never easy.

Syria is no exception, sadly for its people there is little prospect of peace after over six years of war (Wiki refers to the start as March 15, 2011). It is easy to foresee the Syrian diaspora being quite large (bigger than the Palestinian) and with "camps" scattered around its periphery.

Once the Assad regime decided to bludgeon the protestors the die was cast. I do not think there was ever a chance the regime would reform itself. There was a potent "witches cauldron", with a fair amount of external advice and training. Having "kept the lid" on protests and repressing the Homs / Hama revolt in 1982, why would it think the trusted, reliable methods wouldn't work once more?

Yes the "West" has an interest in the region, Syria was rather low down the list of priorities. The USA's interest had a large complicating factor, the defence of Israel - I do find it curious how careful and guarded Israel has been, almost as if the conflict suited it's interests.

Were the policies followed by the USA wise, let alone practical? I am unsure if other Western countries had much impact on the USA, with the exception of France.

Was there a "golden hour / day /month" when external intervention could have ended the civil war? No.