Russia started strengthening its air defense capabilities in Syria after Turkey downed a Russian warplane on Nov. 24, 2015.
Before the incident, Russian forces depended on four deployed multi-role Su-30 aircraft that escorted strike packages. A week after the downing, Russian Su-34 fighter-bombers in Syria were spotted carrying R-27 air-to-air missiles. Russia also took to Syria advanced surface-to-air missile systems, including Buk systems and the long-range and highly capable S-400 system. Moscow also deployed a warship off the Syrian coast near Latakia, to strengthen the defense of its air base there.
Russia has enhanced its air defenses to prevent other countries from entering the Syrian conflict. There are increasing reports that Turkey could be considering direct military intervention in Syria. Even some Arab countries, such as the United Arab Emirates and Saudi Arabia, have made statements about possibly sending troops into the country.
So, in mid-January, Russia reportedly began operating A-50 airborne early warning and control aircraft, which provide better situational awareness and bolster air responsiveness, over the country. Also, four of Russia’s advanced air superiority Su-35 fighter jets arrived in Syria and began conducting combat air patrols. Finally, recently built Pantsyr-S2 systems, which combine missiles and anti-aircraft guns, were spotted in Russian media footage shot at Bassel Al Assad air base, likely replacing or complementing Pantsyr-S1 systems that were delivered earlier in the campaign.
Russia will be able to obstruct the war efforts of those opposed to Syrian President Bashar al Assad. The United States and its allies can still fly airstrikes against the Islamic State, but the prospect of changing targets is greatly hindered by active Russian air support. The United States is even more averse to escalating tensions with Russia. Wishing to avoid losing focus on the fight against the Islamic State, the United States has no desire to confront Russian air power in the skies above Syria.
Turkey and Saudi Arabia, for example, have long sought to oust the al Assad government, but any attempt to unilaterally support the rebels with their own air assets would be met with significant Russian air defenses.