The video, shared on Twitter by CNN correspondent Frederik Pleitgen, displays a TOS-1 heavy flamethrower, which can shoot thermobaric rockets mounted on a T-72 tank chassis.
The footage was captured south of Belgorod, Pleitgen said, which is about 45 miles away from Kharkiv, #Ukraine.
The TOS-1 was first used during the Soviet war in Afghanistan, The Guardian said, and was also deployed in Chechnya and the Syrian civil war.
It can launch two types of warheads incendiary and fuel-air explosives. The latter, also called vacuum or thermobaric rockets, work by using oxygen from the surrounding air to generate a high-temperature explosion.