Western analysts and media have attempted to find rational explanations for Russia's position, suggesting that its main motivation is a desire to preserve its military base in the Syrian port of Tartus and its profitable weapons sales to Damascus. But these factors do not seem to play a leading role.
As the Soviet Union's most loyal ally in the Middle East following Egypt's fall from the Soviet orbit, Syria was probably the largest recipient of Soviet arms among non-Warsaw Pact countries in the mid-1970s. As a result, Syria was able to create a powerful military for that time, equipped almost entirely with modern Soviet weaponry.
As part of an agreement in 2005, Syria placed major orders in 2006 and 2007 with Rosoboronexport, the state arms exporter, for the purchase of weapons worth about $4.5 billion, and that deal continues to define Moscow's military and technical cooperation with Damascus.