Russia kept up its military buildup in Syria on Saturday with a fresh transport flight into a new airbase in the heartland of its regime ally, a Syrian military source told AFP.
It was the 15th straight day that a Russian transport aircraft had flown in troops and equipment to the Hmeimim base in Latakia province on the Mediterranean coast, the source said on condition of anonymity.
"For the past two weeks and again today a Russian cargo plane has landed every morning at Hmeimim," the source said, adding that they all had fighter escorts.
US satellites have recorded increased activity by Russian forces at the base inside the Bassel al-Assad civil and military airport.
Washington and NATO say that recent spottings of helicopters, bombers, ground attack aircraft, tanks and soldiers prove that Russia is building an airbase.
If such a buildup is officially verified -- and more importantly deployed -- it would be the Russia's first military engagement in a distant theatre of war since the Soviet intervention in Afghanistan in 1979.
One senior Syrian official called Russia's military involvement a "turning point" in more than four years of devastating civil war.
"Russia wants to remind the US that its relations with Damascus date back more than 50 years and that this country is in its sphere of influence," the official said.