BBC:
Russia is moving a large amount of military equipment in Syria, signalling preparations for a partial withdrawal, analysts say.
Satellite images reveal a build-up of military vehicles at a Russian-controlled port and airbase in western Syria.
Transport aircraft also appear to have arrived and departed the country in recent days.
BBC Verify has also geolocated videos showing extensive columns of Russian military trucks moving north towards these bases.
The Institute for the Study of War suggests this indicates preparations for a reduction or complete withdrawal of Russian forces.
The Washington-based think tank added that moving military vehicles to its bases may be a precautionary measure while Moscow negotiates with the new government in Damascus.
Russia had a significant military presence in Syria during Bashar al-Assad’s rule – helping him stay in power after the outbreak of the civil war in 2011.
Its two most significant bases are the port at Tartous, established by the Soviet Union in the 1970s and then expanded and modernised by Russia in 2012, and the airbase at Hmeimim, which has been operational since 2015 and was used to launch air strikes across Syria in support of Assad.
Both have become key strategic bases for Russia – giving it easier access to the Middle East, North Africa and the Mediterranean Sea.
However, the fall of Assad has raised questions about Russia’s future presence in Syria. Moscow is seeking to negotiate with the new regime.
On Monday, Kremlin press secretary Dmitry Peskov said there have been “no final decisions” and that Russia was “in contact with representatives of the forces that now control the situation in [Syria]”.
BBC Verify has been monitoring Hmeimim air base activity by using Planet Labs satellite imagery. There are signs of sustained activity, involving sizeable military transport planes. Two large Antonov An-124 aircraft, which may be used to move assets out of Syria, were seen at the base on Friday. They had left by Tuesday, but two large planes were again in the base by Wednesday morning.
