Russian forces have deployed a long-range air-defense system (S-300) in al-Tabqah airbase in Syria’s northeastern Raqqa governorate, where US forces were deployed after expelling ISIS, the Syrian Observatory for Human Rights reported. By the end of 2018, Russia had deployed its S-300 system in Syria’s Deir Ezzor, which is under the control of the Syria regime. This took place at a time when the areas east of the Euphrates were in the hands of the US-backed Syrian Democratic Forces. However, spheres of military influence shifted after former US President Donald Trump having allowed the Turkish army to jump in between Tal Abyad and Ras al-Ain, opening doors to Russian, Turkish and Syrian forces to the east of the Euphrates River. Also, this allowed for the spread of Iranian militias in the countryside of Deir Ezzor on the second bank of the river. The Observatory said that al-Tabqah base “is currently considered a military base and an important location for Russia in the countryside of Raqqa.” According to the UK-based war monitor, the Russian army has deployed advanced S-300 and S-400 advanced missile systems in various areas in western Syria. According to military experts, the S-300 system allows Russia to monitor military movements in northeastern Syria. At the moment, northeast Syria is witnessing drone attacks by Turkey against Kurdish forces, Israeli bombing of Iranian militia sites, and Iranian militia attacks against US military assets east of the Euphrates and at Al-Tanf base.