Thermobaric weapons, sometimes referred to as vacuum bombs or aerosol bombs, are a class of explosive munitions designed to produce exceptionally high temperatures and overpressure by dispersing a cloud of fuel that is then ignited in the presence of atmospheric oxygen. Unlike conventional explosives, which contain both fuel and oxidiser premixed within the munition, thermobaric weapons rely on oxygen from the surrounding air to sustain their explosion, making them significantly more energetic. Thermobaric weapons represent a significant advancement in explosive ordnance technology, offering unique destructive capabilities on the battlefield, particularly in enclosed spaces that amplify the blast and thermal effects.
These weapons are not classified as weapons of mass destruction (WMD) but are highly potent conventional arms due to their ability to generate intense blast waves and thermal effects over a large area.
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1 History
The idea of thermobaric weaponry originated during World War I, with early German tests using incendiary shells and attempts to produce vacuum bombs. During World War II, the German Wehrmacht created the “Taifun B,” a weapon, which dispersed a flammable mixture and then ignited it to produce a strong blast effect. However, these early designs were not extensively adopted. [source, source]
During the Vietnam War, the United States (US) advanced thermobaric weapons by using fuel-air explosives (FAEs), which released an aerosol fuel cloud that produced a powerful explosion after ignition. The USSR then expedited its own research and produced a range of thermobaric munitions, including the rocket-propelled grenades. [source]
FAEs are still in use today. The renowned US AGM-114 Hellfire missile used for precision strikes from ground, sea, and air platforms is a current example of a FAE. Russia actively deploys multiple-rocket launch systems (MLRS) designed to carry thermobaric warheads such as the TOS-1. In 2007, Russia famously tested the largest thermobaric weapon ever made, which had a yield similar to a nuclear bomb. [source]
2 Working Principle
Thermobaric weapons operate on a two-stage mechanism:
1. Dispersion Phase: Upon detonation, a container releases a cloud of fuel aerosol into the atmosphere. This fuel is typically a finely powdered metal or organic molecule that is designed to blend with atmospheric oxygen.
2. Ignition Phase: The dispersed fuel cloud is ignited, causing a high-temperature explosion that consumes atmospheric oxygen. This creates a massive fireball, a prolonged blast wave, and a vacuum effect that can cause severe destruction and suffocation within a wide radius due to oxygen depletion in the blast area.
Thermobaric weapons enable a high destructive power, also in smaller volumes. The 9M133 Kornet thermobaric anti-tank missile warhead has a TNT equivalent of about 22 pounds (10 kg). India’s Defence Research and Development Organisation (DRDO), stated that thermobaric mortar ammunition can produce at least twice the blast impulse compared to TNT shells with similar blast overpressure. [source, source]
Russia’s “Father of all Bombs” (FOAB) bomb test in 2017 was done with a bomb that weighed 7,100 kg, had a blast radius of 300m and a blast effect equivalent to 44 tonnes of TNT. This enhanced blast effect is due to the prolonged combustion and oxygen consumption that amplifies the blast wave beyond the initial explosion. [source]
Thermobaric weapons are more energetic per unit weight than traditional explosives, which rely on a fuel-oxidizer premix. However, they are less effective in oxygen-deficient situations, including underwater or at high altitudes. Compared to traditional explosives, their blast wave lasts much longer and produces heat and mechanical shocks that continue to spread in all directions. [source, source]
2.1 Effects on the Battlefield
Thermobaric weapons produce a multitude of destructive effects:
- Blast and overpressure: Extended duration pressure waves cause structural collapse and lethal damage to personnel.
- Thermal effects: Extremely high temperatures can vaporize human tissue and ignite flammable materials.
- Oxygen depletion: The combustion consumes atmospheric oxygen, creating a vacuum effect that causes suffocation and exacerbates injuries.
- Secondary damage: Pressure waves cause tertiary damage by collapsing surrounding structures, and toxic gases from combustion add to the harm. [source, source]
Thermobaric weapons are very effective in areas like trenches, buildings, and bunkers because the fuel cloud can easily enter and explode inside. It can cause suffocation, lung ruptures, and severe burns in populous or urban locations because of their capacity to produce prolonged blast waves and consume oxygen. Thermobaric warheads with tandem charges are used against armored targets, piercing through reinforced concrete or armor before detonating. [source, source]
Recent documented usage includes Russia’s deployment of the TOS-1A MLRS with thermobaric rockets in Ukraine. Ukraine has also employed thermobaric hand grenades such as the RGT-27S and integrated thermobaric payloads into drone strikes against Russian armored and fortified positions. [source]
3 Examples of Thermobaric Weapons
Examples of thermobaric weapons include: [source]
- TOS-1A (Russia): MLRS that can launch up to 30 rockets armed with thermobaric warheads.
- RPO-A Shmel (Russia): A disposable rocket launcher, effective against buildings.
- ODAB-500PM(Russia): A 500 kg thermobaric bomb, designed to be dropped from aircraft.
- ODS-OD BLU dispenser with BKF ODS-OD bomblets (United States): A cluster bomb system that includes thermobaric bomblets.
- AGM-114N Hellfire (United States): Hellfire missile variant with thermobaric warhead, used for short-range precision strikes.
Other nations known to possess thermobaric weapons include India, which has developed 120 mm thermobaric tank rounds for its Arjun main battle tank (MBT); Serbia, which produces thermobaric hand grenades such as the TG-1, and Ukraine, which manufactures thermobaric grenades like the RGT-27S and has integrated them into drone attacks in its current conflict with Russia. [source, source, source]
Hand-tossed thermobaric grenades pose a potential additional risk if used by terrorist groups, however, there are no documented cases of non-state actors successfully deploying thermobaric weapons to date. This is likely due to the complexity of manufacturing and handling the fuel-air explosive components. Terrorists would need to steal or otherwise acquire devices from nationstates.
By contrast, radiological dispersal devices (RDDs), or “dirty bombs,” are simpler to assemble and have been a greater concern for non-state actors. Unlike thermobaric weapons, RDDs rely on conventional explosives to disperse radioactive material rather than producing a high-energy blast through fuel-air combustion. [source]
3.1 Ethical Considerations
The use of thermobaric weapons spurs debate regarding their compliance with the international humanitarian law (IHL). While they are not banned, there are concerns about use due to the severe and possibly indiscriminate injuries it can inflict, especially in areas with a high civilian population and when high-precision strikes are not used. This can add additional pressure to limit their use solely for military targets without causing unnecessary suffering. [source]
There have been discussions on whether thermobaric weapons fall under prohibitions related to the 1977 Environmental Modification Techniques Convention (ENMOD), given their ability to consume atmospheric oxygen, causing severe damage. The convention prohibits the use of the environment itself as a weapon to cause harm to another state party. However, despite these debates, countries continue to seek the benefits of the deployment of thermobaric weapons, particularly their effectiveness against hardened targets. A prohibition is unlikely to happen in the foreseeable future. [source]
4 Conclusion
Thermobaric weapons are a unique class of explosive ordnance that use atmospheric oxygen to produce devastating blasts and thermal effects. They add strategic value in modern battlefields, particularly in urban and fortified environments. However, their use raises ethical questions due to the severity of injuries and potential civilian harm. Despite these concerns, they will likely remain a critical tool for militaries due to their effectiveness.
