Russia has reportedly sent a warship carrying a marines unit to Syria's Mediterranean port of Tartus, where Moscow has a naval base.
Citing military sources, Russian media reported on Sunday that the Novocherkassk landing ship left the port of Novorossiisk in the Black Sea and is due to arrive at Tartus in the early days of January.
Two other warships, the Azov and Nikolai Filchenkov, have also reportedly been dispatched to Syria from Russian naval bases since Friday.
Reports say Moscow is preparing a plan to evacuate Russian nationals living and working in Syria in case the situation in the country worsens.
Two weeks ago, Russia's Defense Ministry announced that a fleet of Russian warships had been sent from the Baltic port of Baltiysk to the Mediterranean Sea near the Syrian waters.
It said the flotilla includes the frigate Yaroslav Mudry, the landing ships Kaliningrad and Alexander Shabalin, as well as two other vessels.
Russia, a key ally of Syria, has a small naval maintenance facility at Tartus port.