[archy]

Didn't the Ruskies try this in Afghanistan and failed miserably?

Indeed they did. After Jimmy Carter armed the muslum extremists via Operation Cyclone.

[oilwatcher]

Easier for a large mechanized war machine to dominate in the relatively open desert areas of Syria than in the mountains of Afghanistan ... also presumably the US won’t be supplying arms to ISIS, beyond what they’ve already seized from our abandoned Iraqi bases and “moderate” allies ....