Thermobaric rockets are a "fuel-air" weapon system. When fired, the rockets disperse a cloud of flammable liquid into the air around the target, and then ignite it.
“The results are devastating — not only is the explosion significantly longer and the shockwave significantly hotter and stronger than a conventional warhead, but all the oxygen in the near vicinity is also consumed, creating a partial vacuum. This makes them horrifying weapons to use against infantry and entrenched personnel in bunkers and caves—exactly what the TOS-1 was designed for,” Popular Mechanics noted.
“A full salvo of the system’s 24 rockets will make a rectangle 200 meters by 400 meters – a bit more than eight city blocks – hell on earth for anyone caught inside.”
The TOS-1A Heavy Flamethrower System is a 220mm 24-barrel multiple rocket launcher and thermobaric weapon mounted on a T-72 tank chassis.
It was designed for defeating enemy personnel in fortifications, in open country, and in lightly armored vehicles and transport. First combat tests took place in 1988-1989 in Afghanistan.
The combat system, which consists of the combat vehicle, rockets, and loading vehicle, was developed in 1979 by the design bureau of the Transport Machine Factory in Omsk and was named TOS-1. It remained a secret development for a long time.