Home / Europe / War In a Vacuum – The complex legality of Russia’s TOS-1A weapon systems

War In a Vacuum – The complex legality of Russia’s TOS-1A weapon systems

2 April, 2022

by Sam Biden, Global Leadership Fellow

Deployment & use of thermobaric weaponry

On March 9th 2022, the Russian Ministry of Defense (RMoD) confirmed the use of their TOS-1A weapon systems or ‘thermobaric weaponry’ in the ongoing Russia-Ukraine conflict. Footage was captured of a Russian TOS-1A system firing towards the port city of Mariupol where much of the conflict has been taking place. A multitude of rockets can be seen being fired towards the city leaving behind a trail of smoke as they were allegedly launched at civilian targets. The launch comes after a stalemate within Mariupol caused by Ukraine’s refusal to put down their arms within the city to allow for full civilian evacuation.

What is a thermobaric weapon?

A thermobaric weapon, also known as ‘vacuum bombs,’ release a large cloud of flammable gas that can cause huge explosions. They are designed to suck in oxygen from the surrounding air and create a high-temperature explosion in two stages. The first stage distributes an aerosol of fine materials from carbon-based fuel, this is then ignited and creates a cloud with a vast outwards shock wave followed by a vacuum that sucks up all surrounding air.  These types of blasts last far longer than any conventional explosive and are capable of vaporizing any human within their impact radius instantly. Dr Marcus Hellyer states that they are typically used for destroying defensive positions, yet acknowledges that their use elsewhere can render any building completely destroyed.

The thermobaric weapon in question, the TOS-1A, is a heavy ‘flamethrower’ (although not in the traditional sense of the term) system adopted by Russia in 2001. The weapon is designed for fire support of advancing ground forces. It can also be used for clearing out large areas where opponents have military objectives. This is achieved by the clearing of buildings, fortifications and bunkers.

With their clear capability for mass destruction in mind, the legality surrounding their use is far more complex than understanding their function.

Complex legality of thermobaric weaponry

Thermobaric weaponry does not exist within a strictly defined legal paradigm like other forms of weaponry. For example, nuclear weapons, landmines, chemical weapons and certain forms of bullets all have hard codification as to their legality. The issue of finding hard codification where an easy assessment of the legality of thermobaric weaponry can be made leads to two general observations. Firstly, the use of generally applicable international humanitarian law (IHL) and second, the attempt to fit thermobaric weaponry into an already prohibited specific weapon classification.

  1. Generally applicable IHL

In the most basic format, the principles of distinction can offer a quick solution to the question of whether thermobaric weaponry is lawful in some instances, but this does not provide an elegant solution. For example, Article 2 of The Protocol on Prohibitions or Restrictions on the Use of Incendiary Weapons states;

(2) “It is prohibited in all circumstances to make any military objective located within a concentration of civilians the object of attack by air-delivered incendiary weapons”

(3) “It is further prohibited to make any military objective located within a concentration of civilians the object of attack by means of incendiary weapons other than air-delivered incendiary weapons, except when such military objective is clearly separated from the concentration of civilians and all feasible precautions are taken with a view to limiting the incendiary effects to the military objective and to avoiding, and in any event to minimizing, incidental loss of civilian life, injury to civilians and damage to civilian objects.”

From the above prohibitions, further attacks of Mariupol using thermobaric weaponry could constitute a violation of the Protocol. Because of the nature of the use of fuel and ignition, some have argued that these forms of weaponry can be classed as incendiary, meaning Russia could be liable under general IHL for any indirect or indiscriminate consequences for civilians. However, as there are no concrete current reports as to civilian loss, whether life or object-based from thermobaric weaponry, no legal conclusion can be made regarding this specific instance.

Because thermobaric weaponry has the potential for wide and indiscriminate destruction, even if not intended, Article 51 (5, a) of the First Additional Protocol can similarly apply, the following attacks are regarded as indiscriminate:

(a) an attack by bombardment by any methods or means which treats as a single military objective a number of clearly separated and distinct military objectives located in a city, town, village or other area containing a similar concentration of civilians or civilian objects

The vacuum element of thermobaric weaponry leaves the above Article reasonably open for engagement should the use of the weaponry cause the above effect. While this does not strictly answer the question of whether thermobaric weaponry as a means of warfare is unlawful, it does offer legal redress for indirect victims of the devastating blasts these weapons can deliver.

  1. Specifically applicable IHL

While generally applicable IHL certainly offers some basis for the protection of indirect and incidental, indiscriminate use of thermobaric weapons, specific provisions outlawing their use entirely as seen above is still an issue. The first example can be made with reference to the use of expanding bullets. The 5 part test for the use of expanding bullets is as follows:

  1. The perpetrator employed certain bullets.
  2. The bullets were such that their use violates the international law of armed conflict because they expand or flatten easily in the human body.
  3. The perpetrator was aware that the nature of the bullets was such that their employment would uselessly aggravate suffering or the wounding effect.
  4. The conduct took place in the context of and was associated with an international armed conflict.
  5. The perpetrator was aware of factual circumstances that established the existence of an armed conflict.

One can see how point 3 could be similarly applied to thermobaric weaponry if the provisions applied vice versa. The flammable effects of thermobaric weaponry could uselessly exacerbate any previous injuries civilians have, given the nature of the weaponry is for territorial clearance. Therefore, the 5 elements could be applied to the comprehensive list of prohibited weaponry due to be contained in the annex of the Statute of the International Criminal Court. The above basis for the addition of thermobaric weaponry to the annex overlaps with the useless aggravation element found in the expanding bullets test. At a stretch, thermobaric weaponry could be unlawful if the conclusion with its addition to the annex uses the same logic as the legality of expanding bullets. This is supported by the notion of causing superfluous harm or unnecessary suffering. Even if you are not vaporized by thermobaric weaponry, the burning and chemical nature of its use do somewhat corroborate with useless aggravation. However, official recognition of this link does not currently exist.

Incendiary & Chemical weapon classification

Reclassification and interpretation of thermobaric weaponry as either incendiary or chemical weapons is the second example regarding specific prohibitions.

An incendiary weapon is defined as:

(1) “any weapon or munition which is primarily designed to set fire to objects or to cause burn injury to persons through the action of flame, heat, or combination thereof, produced by a chemical reaction of a substance delivered on the target”.

 The ignition element of thermobaric weaponry can lead to the conclusion they are incendiary weapons, however, this yields the same result as a violation of Article 51 (5, a). Because of this, their effects are legal so long as their application is only relevant to combatants. Deployment of these weapons by air in which civilian harm may occur is still prohibited.

A chemical weapon is defined as:

(a) Toxic chemicals and their precursors, except where intended for purposes not prohibited under this Convention, as long as the types and quantities are consistent with such purposes;

(b) Munitions and devices, specifically designed to cause death or other harm through the toxic properties of those toxic chemicals specified in

subparagraph (a), which would be released as a result of the employment of such munitions and devices;

Unlike incendiary weapons, the use of chemical weapons is an absolute prohibition. The use of chemical weapons, whether the targets are combatants or civilians, is irrelevant. It is the use itself that is a violation of IHL. Due to the dispersion of toxic fuel into the air and small spaces through the vacuum effect, it could be argued that thermobaric weaponry has some form of chemical use even if this is not a primary function. However, this conclusion is incorrect as per the definition of a chemical weapon, the chemical element must be intrinsically linked to causing death or other harm. Since the intention of thermobaric weaponry is not chemically based but more incendiary and territorial clearance based that is achieved through a vacuum, thermobaric weaponry cannot reasonably be argued as prohibited under the Chemical Weapons Convention.

Is the use of thermobaric weaponry unlawful?

While the assessment of general and specific IHL only leaves more questions, the short and safe answer is that Russia’s sole use of thermobaric weaponry is permitted by IHL. Russia’s manufacturing, development, collection and deployment of thermobaric weaponry is entirely lawful thus far. The only smoking gun in the debate is with indiscriminate use of these weapons, however, any indiscriminate use of weaponry is prohibited regardless, so thermobaric weaponry is not special in this regard. To state thermobaric weaponry as unlawful, a specific provision that mentions their capabilities and use would have to be implemented into IHL directly.

Image: Heavy flamethrower system TOS-1A during the “Armiya 2020” exhibition (Source: Kirill Borisenko via CC BY-SA 4.0)


About Sam Biden

Sam Biden is a double law graduate from Aberystwyth University whose degree focused primarily in the enforcement and protection of civil liberties. His research surrounded areas such as data protection, protection from unlawful interference, environmental law, freedom from torture, inhuman or degrading treatment, humanitarian law and natural law jurisprudence. Sam’s areas of interest include the advocating for the protection of digital liberties, ensuring of safe passage and treatment for the victims of the migration crisis and the drafting of solutions to repair corporate exploitation resulting in human rights violations and exacerbated climate damage.