Riyadh and Tehran are rivals in almost everything, but they support Russia's efforts to give Washington a black eye.
According to the authors, Saudi Arabia and Iran support Russia in order to weaken US interests.
Both countries also want to strengthen their influence in an increasingly multipolar world order.
Russian presidential spokesman Dmitry Peskov said the Kremlin has no information about Russia's purchase of drones from Iran.
Iran denied accusations of handing over the drones to Russia.
Russian leader Vladimir Putin said that relations between Russia and Iran are developing in all directions.