Vladimiri Putin, Russian president who disclosed this development, said the killing is a visit revenge for the killing of Russian army general and Sargent.
Putin further warn that Russia will not take it lightly with anyone who dare to attack Russia military.
"Russia took vengeance for the death of its general and sergeant. Su-34 fighter-bombers destroyed an underground bunker of terrorists from the Islamic State organization in Syria. 30 militants were destroyed, and among them was the field commander, who organized the bombing of the Russian column on August 18. On that day General Gladkikh and young sergeant Milshin died. The organizers of their murder were hiding in dungeons in the province of Deir ez-Zor, which is controlled by US troops.
Anyone who dares to raise hand on the Russian military will inevitably pay for this. Like anyone who tries to bring war back to the land of Syria. Russia will stand on guard of peace and quiet life of civilians." Putin said via Facebook post
The killing is come a day after Russian President announce the successful testing of Hypersonic missiles.