Russia removed the S-300 missile defense system from Masyaf in north-west Syria recently, to bolster its military offensive in Ukraine, facilitating a strike on targets there last week, attributed to Israel.
Images released by an Israeli satellite company showed the missiles that were previously deployed near the military research facility that was targeted in the strike, were no longer in position.
It is unclear how many of the 24 S-300 batteries deployed to Syria were removed but some clearly remain and can be used to limit Israel's ability to strike against targets in Syria and Lebanon.
Still, removing the air defense system from Masyaf is consequential because of the city's strategic importance.
Masyaf has become the primary center for the production of Syrian and Iranian precise missiles and rockets, for use by Hezbollah and other Shi'ite militia groups
The military complex there includes large underground bunkers where Syria stores its missile and rocket arsenal, which arrives through the port in near-by Tartous.
It is likely that Israeli intelligence was aware of the Russian redeployment of the S-300 battery, and took advantage of the opportunity to strike, last Thursday.
The Russian system has the capacity to shoot down not only attacking aircraft but also incoming missiles, including long-range cruise missiles. Their removal allowed the use of special munitions, which would have otherwise been impossible.
Syrians operate the S-300 systems having been trained in Russia and Syria but are under the command of Russian "military advisors."
In a reported Israeli strike on the Masyaf facility last May, a S-300 missile was launched at attacking aircraft, after it had released its load.
Although no aircraft was hit or even locked on to by the system, the IDF was concerned that the Russian policy in Syria had changed because of the position taken by Israeli leaders in support of Ukraine, after it was invaded by Russia last February.
Israeli officials were concerned that the Russians were sending a message that they would no longer allow freedom of operation over Syrian skies.
Jerusalem was told by Moscow at the time, that the May incident was the result of an internal mis-understanding in the Russian-Syrian air defenses, protecting the Syrian regime. No such incident occurred, since.
Syria will likely replace the missing S-300 battery with alternative defenses to protect the military instillation in Masyaf. A different Russian battery might be deployed, or perhaps the Iranians may attempt to position their surface to air missile systems, if Syria agrees.
The Iranians have the Bavar-373 missile defense system, that is compatible with the Russian S-300, as well as their Khordad 15 – which has a shorter range and have attempted to deploy them to Syria.
Israel was reported to have attacked such missile systems as they were being transported. Some through the port in Tartous, which has also come under attack.
Although it remains unclear how many of the S-300 batteries were redeployed to assist the Russian invasion of Ukraine, Israel now has more freedom to operate than it had had since 2018 when the S-300 missile system was first delivered to Syria.
The IDF and particularly its air force would now have to examine what defenses will be deployed by Syria and Iran.