Russian President Vladimir Putin has signed a federal law on ratifying an agreement between Russia and Syria on the deployment of an aviation group of the Russian armed forces in Syria, the Kremlin said on Friday.

Both houses of Russian parliament had approved the August 26, 2015, agreement this month.

The law was passed by the State Duma (Russia’s lower house of parliament) on October 7, 2016, and approved by the Federation Council (Russia’s upper house of parliament) on October 12, 2016.

The agreement signed in Damascus regulates the terms of deployment of Russia's air group in Syria.

The Kremlin's press service notes that the Russian air group is stationed at the Hmeymim airfield in the Latakia province free of charge at the request of Syria.

Under the agreement, Russian military personnel will gain immunity identical to that provided by the Vienna Convention on Diplomatic Relations.  Russian troops will also not be subject to border checks when entering Syria.

Russia launched an operation in Syria to combat terrorism on September 30, 2015 at the request of Syrian President Bashar Assad.  In March 2016, Russian President Vladimir Putin ordered to withdraw the main part of the Russian air group from Syria.