Al Qaeda and allies form coalition

to battle Syrian regime in Idlib

"This is not the first time Al Nusrah has advertised its use of American-made weapons. In December of last year, the group posted a video and pictures of its fighters using a TOW missile in Idlib. It is likely the weapons were captured from Western-backed groups, which have received some American-made arms."
So if weapons supplied to the FSA end up with Jabhat al-Nusra, there is a real danger that they will use them...to fight Assad.