Russian President Vladimir Putin has ratified an agreement with Damascus for the indefinite deployment of a Russian Air Force group near Syria's coastal city of Latakia.
The agreement was signed in Damascus in August 2015, just days before Russia began launching air strikes against Syrian rebel fighters in order to support Syrian President Bashar al-Assad's regime.
The deal stipulates that Russian military aircraft and aviation crews deployed at Syria's Hmeimim airfield are there at the request of the Syrian government.
It also grants diplomatic immunity to Russian personnel deployed at Hmeimim and their family members.
The Russian Defense Ministry says it also is working to make its Syrian naval station at the port of Tartus a permanent base.
Russia has significantly built up its military presence in Syria since the collapse on September 19 of a cease-fire agreement brokered by Moscow and Washington.