Russian warships could be seen at a naval facility in Tartus earlier this month, but on Monday, they were gone.
Summary
Satellite images show Russian warships missing from the Tartus naval base in Syria after rebel forces ousted Bashar Assad in a swift offensive, ending his 13-year rule.
Earlier images from December showed warships docking and leaving intermittently, but all vessels were gone by December 9.
The loss of Tartus and the nearby Khmeimim airbase, key to Russia's military logistics, would be a significant blow.
Moscow has not confirmed its forces' status.
The U.S. attributes Assad's downfall to weakened support from Russia, Iran, and Hezbollah.