Two Russian navy ships are completing preparations to sail to Syria with a unit of marines on a mission to protect Russian citizens and the nation's base there, a news report said Monday. The deployment appears to reflect Moscow's growing concern about Syrian President Bashar Assad's future.

The Interfax news agency quoted an unidentified Russian navy official as saying that the two amphibious landing vessels, Nikolai Filchenkov and Caesar Kunikov, will be heading shortly to the Syrian port of Tartus, but didn't give a precise date.

Each ship is capable of carrying up to 300 marines and a dozen tanks, according to Russian media reports. That would make it the largest known Russian troop deployment to Syria, signaling that Moscow is becoming increasingly uneasy about Syria's slide toward civil war.