The US began using the BLU-118B and BLU-118S bombs in Afghanistan, where their fuel-air explosive action was deadly against caves and bunkers. Because the fuel has a chance to spread through cracks or narrow passages in bunkers, caves, and tunnels, and the fire that detonates the fuel easily follows the same path, these weapons are particularly destructive. Human rights groups have denounced thermobaric weapons as unusually cruel since they can literally suck the air out of a person's lungs.--Stephen V Cole
The media has become enchanted with the word "thermobaric", a term meaning a blast of heat and pressure created by a fuel-air explosive type bomb. The US has used fuel-air explosives since Vietnam, mostly as large aircraft bombs. The Russians, who coined the term "thermobaric", use smaller weapons of this type carried by shoulder-fired rockets to support infantry attacks on buildings or bunkers. The fuel-air or thermobaric concept is fairly simple. The weapon disperses a cloud of flammable or explosive fuel, then detonates it. Anyone who has ever seen a house destroyed by the explosion of natural gas from a faulty pilot light knows the result. A huge wave of pressure which can blow out walls and kill people. While heat is involved in the explosion, pressure is the major active ingredient.