Sources link Israel to sharing at the least, intelligence with some fighting Assad, whether one believes it or not is another thing. Sources like Debka.
Check this out, I thought the name was familiar, they thought they killed the same guy last summer.
https://en.wikipedia.org/wiki/Samir_Kuntar#Death
See the last part of the story, “attempted assassination”, I thought it was reported they did get him but they must not have; so this time??