Without a no-fly zone, assistance is useless. Iranian supply must be choked off. I'm not suggesting that planes in flight be shot down, although that could come to pass. Syrian airports have to be disrupted so that nothing can land. Cruise missiles and stand-off ordnance can accomplish this without risking pilots.
27 injured in fire, explosion at former air raid shelter in Hamburg, Germany (DPA)
from the article: Obama's decision to arm Syrian rebels is too little, too late