Despite years of protest from Israel and the United States, the Russians have delivered to Assad SA-22 (Pantzir) SAMs and SSN-26 (Yakhont) land-to-sea cruise missiles.
IDF has not yet tested its electronic jamming systems on the SA-22, which the Russians claim are virtually immune to jamming. The SAMs have short range, though, and can be overwhelmed by massive attack from about thirty miles. They cannot protect all of Syria, but they are effective for small installations.
The SSN-26 is a much more problematic weapon. It turns on its radar close to its target, and is therefore not susceptible to jamming. So far Syria has been able to make little use of them, as it lacks aircraft for launching such heavy missiles and can only drop them within visual range. The Israeli Navy cannot reliably detect SS-N-26 on approach, as the missile skims just fifteen feet above the waters.
Once, Israel was concerned about the possibility that the Arabs would all retaliate together for our targeted attacks. Today the situation is reversed: we have to threaten Syria with blanket reprisals for targeted attacks on our ships with Yakhonts.