See title question. As far as I can tell from my reading, a key mechanism of thermobaric lethality seems to involve its chemical compounds. For example:

If the fuel deflagrates but does not detonate, victims will be severely burned and will probably also inhale the burning fuel. Since the most common FAE fuels, ethylene oxide and propylene oxide, are highly toxic, undetonated FAE should prove as lethal to personnel caught within the cloud as with most chemical agents. (Wikipedia)


Imagine taking a deep breath then submerging yourself in water. Then imagine having all of the oxygen forced instantaneously from your body. Try to inhale again. But instead of cold water filling your lungs, toxic, flammable particles start killing you from the inside out… (Independent.co.uk)

While the explosion itself is perhaps comparable to a conventional explosive, it seems that the chemical lethality is a non-trivial component. Wouldn’t this classify it as a chemical weapon?

Lastly, and maybe this alludes to the answer:

the only reason thermobarics aren’t a war crime in fact is because the international community has yet to officially name them as cruel weapons (Forbes, 4 years old)

Any insight would be great.


2 Answers 2


Thermobaric weapons are conventional weapons.

They range in size from grenade launchers to large bombs.

All weapons except for specifically chemical, biological, radiological and nuclear are considered conventional.

The chemicals used in explosives and produced by explosives aren't picked out for non-toxicity, but that alone doesn't turn a weapon into a chemical one. According to the Chemical Weapons Convention, a weapon is chemical when its effect comes solely or mainly from its toxicity. Thermobarics are mainly destructive through their explosion.

The fuel used is toxic, but so are a lot of rocket fuels. The toxicity profile for Ethylene Oxide, used in thermobaric weapons, is similar to that of Hydrazine, commonly used in rockets and fighter emergency power units. Both have a prolonged exposure limit of 1 ppm and may be lethal above 100 ppm. Practical chemical weapons are lethal in the ppb range.

However, there are some treaties restricting the use of some conventional weapons by their signatory. These include anti-personnel land mines, cluster munitions, and small explosive projectiles.

The first such treaty still in effect is the St. Petersburg Declaration of 1868, which prohibited explosive and incendiary projectiles under 0.4 kg. Notably, it was initiated by the very nation that created said "explosive bullets".

The most recent is the Convention on Cluster Munitions of 2008. Cluster bombs are definitely conventional, but result in excessive collateral damage. Not all countries are signatories to either or both, and treaties only apply to conflicts between signatories.

There currently isn't any similar treaty for thermobaric weapons.


While thermobaric weapons may or may not be conventional, their use by the civilized countries is generally frowned upon and is considered unconventional.

To answer all aspects of your question, Putin’s existence might be short-lived in case he chooses to use it on Ukraine in a desperate attempt to achieve his objectives.

  • 4
    The U.S. army was reported to use lots of depleted uranium (many would frown upon this as well) in Iraq war in 2003, but Bush Jr still got his second term...
    – No One
    Feb 27, 2022 at 5:08
  • theguardian.com/world/2014/jun/19/…
    – No One
    Feb 27, 2022 at 5:10
  • 10
    Thermobaric weapons have been used extensively in Iraq, Afghanistan, and Syrian/ISIS wars, by all parties that had access to them.
    – Therac
    Feb 27, 2022 at 8:02
  • 3
    @user24711 That is true, but Bush did not claim he came to liberate those bombed people from their opressing government in a small military operation that is not even an invasion. Putting Kyiv into rubles is completely incompatible with the story he tries to make at home about the brother nation he liberates. And it really does not matter that much whether he will achieve that with thermobaric missiles or carpet bombing. Even using normal Grad salvos against cities full of civilians is a war crime. Feb 27, 2022 at 16:33

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