I personally don't understand the Syrians. Recently Israelis struck another research facility. This is confusing to me because during the civil war, the rebels dug massive tunnel networks in underground caves. Some of these being very extensive and deep underground. With Iran's experience in this field, Iran could easily extend these networks and setup vital locations, like research facilities there. Or they could be used to keep mobile launchers for air defense units. Another option is to keep Iranian drones or missiles on Russian protected sites, like Hmeimim airport.
Iran could also transfer small scale air defense systems to Lebanon, since Israeli jet usually fly over Lebanon to launch missiles to Syria. They often fly low, then fly over the Golan Heights, unleash their missiles and then fly back to Israel. MANPAD ambush teams could easily spot the jets while they're flying low and try to shoot them down. For some reason though this never gets done.
Another thing i wonder about Libya is why they don't liberate the rest of Idlib. Their army seems capable but I guess the Turks don't want Al Qaeda militants flooding into Turkey as they flee. I suppose that with the current economic situation in Turkey, that Assad is waiting for a pristine opportunity ?
But then there's Al Tanf and the oil fields in Deir Ezzor controlled by SDF. I don't understand why Assad doesn't unleash missiles and drones at these sites. I mean yes he's hoping that one day he can regain control and doesn't want to destroy the oil facilities but come on he should give them an ultimatum, "either give us our oil facilities back or we'll destroy them"
On the other hand, Syria has been through so much in the last decade that they're basically just happy to be alive I guess and trying to keep their economy from completely collapsing. Can't really blame Assad considering the fact that his regime barely survived just a few years ago.
I'm sure that Iran would be willing to help Assad retaliate everytime the Syrians launch airstrikes but if the Syrians are reluctant and unwilling, then what can you do ?
When Syria left Lebanon, it lost strategic depth for air defense zone, that is because of terrain(there is Mountain chain between border), Syria now has big problems since Israel can fly all the way to mediterrain sea undetected, they Just pop up fire missile and fly back to lower atlittude... Syria would need constant presence of AWACS in Med. Sea to cover this gap or some OTH radar on the North. There is option to put some short to medijum AD systems a long the border, which Syria did at some degree, but this still is not solution for Israel aircrafts since they fire missile from long ranges, from Lebanon or Med Sea, to be honest Syrian AD has improved their time of reaction, and they shot down most of the missiles.