Putin ratified the August 2015 intergovernmental agreement on the deployment of the Russian Armed Forces' air group in Syria in October 2016.
Under the agreement, Russian military personnel gain immunity identical to that provided by the Vienna Convention on Diplomatic Relations. Russian troops are also not subject to border checks when entering Syria.
Putin approved a decree on signing a protocol to the agreement in December 2016. The protocol regulates Russia’s aviation group deployment in Syria, its movable and immovable assets in the country and matters connected to the counterterrorist operation itself, according to the Kremlin press service.
Russia began its counterterrorist air campaign in Syria on September 30, 2015, at the request of Syrian President Bashar Assad.