Since the collapse of a weeklong ceasefire late last month, Russia is believed to be significantly building up its military forces and capabilities in Syria, with suggestions the country has doubled its supply runs into the country since the ceasefire fell apart.
A significant portion of this is believed to have been related to the Russian deployment of S-300 anti-aircraft missile systems into the area around their naval base at Tartus, a deployment which Russian officials have tied to US threats of “non-diplomatic” action against them.
The deployment dramatically increases Russia’s control over Syrian airspace in the event of overt hostilities with the US, and virtually eliminates the possibility that the US could declare a “no-fly” zone over Syria and believe it couldn’t be heavily contested.
The deployment was seen as an effort to deter unilateral military action by the US against Russian and Syrian forces in Syria, though the State Department has insisted that such discussions are ongoing within the US government irrespective of Russia’s warnings.
Since the ceasefire’s collapse Russia has also deployed more advanced warplanes into their bases in Syria, with the advanced fighter-bombers seen as much less vulnerable to enemy aircraft should such a battle suddenly erupt.