Using Environment as a Weapon: The Case of Vacuum Bombs

Using Environment as a Weapon: The Case of Vacuum Bombs

[Archita Sharma and Chytanya S Agarwal are undergraduate students at the National Law School of India University, Bangalore.]

The Ukraine-Russia conflict has shown that international armed conflicts are not a distant reality in the 21st Century. The war continues to cause immense suffering and devastation, raising several international law concerns.

The alleged use of thermobaric weapons by the Russian forces against Ukraine creates concerns regarding the validity of their use under international humanitarian law (jus in bello). Thermobaric weapons, also called fuel-air bombs or vacuum bombs, are considered to be the most devastating non-nuclear weapons developed to date. Currently, their use is not explicitly banned under the Hague and the Geneva Conventions (including the Additional Protocols). However, they are subject to recognized principles of warfare such as principles of distinction, proportionality, military necessity, and humanity. Under these principles, the use of certain technologies per se is not prohibited and the rule’s violation is context-dependent and hinges on the manner of their use.

Today, environment modification techniques are being used for peaceful purposes. It is important to ensure that the same technologies are not diverted towards destructive use. Therefore, in this post, we provide an enviro-legal perspective on the use of thermobaric weapons under the Convention on the Prohibition of Military or Any Hostile Use of Environmental Modification Techniques, 1976 (hereinafter “ENMOD” or “the Convention”). We argue that the belligerent use of thermobaric weapons is per se violative of ENMOD. For the purposes of this blog, we consider only fuel-air explosive thermobaric weapons as they cause maximum destruction. This excludes smaller handheld versions such as Rocket Propelled Grenades (RPGs).  “Thermobaric weapons” shall be construed accordingly. 

ENMOD was signed in the aftermath of the Vietnam war with the intent of curbing the arms race and preventing the use of the environment as a weapon in warfare. It was initiated by the USA and Russia (then USSR) and currently has 78 members, including Ukraine. There are two conditions under ENMOD that need to be satisfied for a valid prohibition. First, the technology should constitute an Environmental Modification Technique (“EMT”) under Article II. Second, it should meet the damage threshold under Article I. We argue that thermobaric weapons satisfy both these conditions. Firstly, the technology of large-scale fuel dispersion used in thermobaric weapons and the subsequent elimination of atmospheric oxygen constitutes an EMT. Secondly, their injury mechanisms have “severe effects” and meet the threshold under Article I. 

Thermobaric Weapons as an Environmental Modification Technique

ENMOD has certain “Understandings” annexed to it. These are non-binding texts submitted by the Conference of the Committee of Disarmament to the UNGA at the time of adoption of the Convention. This was done with the aim of providing assistance in interpreting the terms used in the Convention.

The “Understanding to Article II” reads as, “following examples are illustrative of phenomena that could be caused by the use of environmental modification techniques as defined in article II of the Convention.” It further mentions volcanoes, earthquakes, the formation of clouds, and precipitation as some examples. We argue that it is amply clear from the text that the list does not illustrate what an EMT is. Instead, it only lists certain consequences that could occur because of the use of such techniques. However, some scholars, like Karen Hulme, have misunderstood these as examples of the technique itself. We must clarify this distinction at the outset because the Convention nowhere mentions techniques that can be considered as examples of EMT. Therefore, the definition under Article II provides the sole test to establish whether a technique qualifies as an EMT or not.

Article II of the Convention reads as, 

“The term “environmental modification techniques” refers to any technique for changing – through the deliberate manipulation of natural processes – the dynamics, composition or structure of the Earth, including its biota, lithosphere, hydrosphere and atmosphere, or of outer space.” 

We argue that the technology used in thermobaric weapons changes the composition of the Earth’s atmosphere through the deliberate manipulation of natural processes. Therefore, it satisfies the above test and constitutes an EMT.

Thermobaric weapons primarily work with a two-step mechanism to cause an enhanced explosion. The first step is an anaerobic phase which releases an oxygen-deficient fuel mixture to form a cloud of explosive material over the targeted region. The fuel cloud also mixes with the atmosphere of the region and quickly gets in the cracks and crevices in buildings, caves, and bunkers. It enlarges the range of the blast. This distinguishes thermobaric weapons from conventional weapons as conventional weapons are inadequate to destroy hard structures such as caves and bunkers. Thermobaric weapons, by dispersing the fuel inside hard structures prior to the explosion, overcome this shortcoming.

Milliseconds later, the second step follows which is a massive blast caused by the detonation of the fuel cloud. This is an aerobic stage that uses the modified  atmospheric  to sustain the blast for a longer duration resulting in a massive fireball of temperatures as high as 3000 degrees centigrade.

The creation of a cloud of explosive fuel and its mixing with the surrounding air amounts to changing the composition of the atmosphere of the region. Further, the specific use of atmospheric oxygen to create exceptionally high temperatures is deliberately manipulating the natural processes of the atmosphere. The massive explosion creates a vacuum or rarefaction in the targeted region. The creation of fuel cloud and the subsequent vacuum is clearly tampering with the composition of the atmosphere – which naturally is 78% nitrogen and 21% oxygen in the troposphere. This is not the case with traditional explosives due to two reasons. First, they are designed to entail damage only through blast and fragmentation and not through thermal effects – which is limited only to its immediate area of detonation.  Resultantly, their interaction with atmosphere and atmospheric oxygen is of a scale much smaller when compared to thermobaric weaponry which can potentially change the entire atmosphere of a region. Second, traditional explosives use oxygen for last-stage combustion of residuary explosive particles.  Mere use of oxygen for combustion does not change the atmospheric composition and hence would not qualify as an EMT under Article II. 

Arthur Westing, while discussing environmental warfare, regarded the use of herbicides and various levels of fog generation as EMT. The use of herbicides in a manner that disrupts the ecological balance of a region has been accepted as an EMT by the Second Review Conference of ENMOD as well. This shows that technological sophistication is immaterial so long as the technique’s effect is the modification of the environment’s natural processes and its composition. 

Injury Mechanisms and “Severe Effects”

Since thermobaric weapons constitute an EMT under Article II, on satisfying the requirements mentioned in Article I of the convention, their use will be prohibited under the Convention. A plain reading of Article I, according to the ICRC, shows that it prohibits the use of EMT based on a three-pronged analysis. First, the use of the technique should be for hostile or military motives. Second, it must be used against another State party to the convention. Third, the use of the technique should cause “widespread, long-lasting or severe” effects. While the belligerent use of thermobaric weapons against state parties squarely falls within the first two prongs, we argue that their injury mechanisms constitute “severe effects” as well. “Severe effects” has been defined under “Understandings regarding the Convention” as “involving serious or significant disruption or harm to human life, natural and economic resources or other assets.”  Three points ought to be noted before interpreting the “effects” clause of Article I.

First, the terms “widespread, long-lasting or severe effects” should be interpreted as per the definitions given under the “Understandings” due to the lack of judicial precedents and the absence of additional sources of interpretation. Other international law instruments such as Articles 35(3) and 55 of the 1977 Additional Protocol to the Geneva Convention (“AP-I”) also mention “widespread, long-term and severe damage to the environment.” However, the interpretation of these terms in ENMOD cannot be done by relying on the AP-I due to different contextual uses of the terms in both the treaties. While ENMOD aims to prohibit the use of the environment as a weapon, the AP-I protects the environment per se. “Long-term” used in AP-I indicates several decades whereas “long-lasting” under the “Understandings” is explained as only “a period of months, approximately a season.” This highlights the fallacy in resorting to the explanations and the negotiation history of Additional Protocols to understand the text of ENMOD. Moreover, the 1987 commentary on AP-I states that the three terms do not have the same definitions as the corresponding terms under ENMOD. The “Understandings” clearly state that the interpretations are “intended exclusively for this Convention,” further highlighting the need to construe these terms in the context of ENMOD, to the exclusion of other treaties.

Second, while Article I of ENMOD prohibits hostile modification of the environment, the effects of such modification need not be only environmental. The term “effects” in Article II is unqualified. Therefore, drawing from the “Understandings” damage to human life, economic resources, nature, and the environment all need to be considered while determining the effects of an EMT. 

Lastly, the Convention provides a “disjunctive” threshold by using “or” instead of “and” between the words “widespread”, “long-lasting” and “severe”. In the case of a disjunctive threshold, the coexistence of all three conditions need not be fulfilled. This implies that even if the damage has only “severe” effects, the EMT’s belligerent use against a state party becomes prohibited.

The damage caused by thermobaric weapons is twelve to sixteen times greater as compared to conventional high explosives. They also form a category distinct from incendiary weapons, as the former detonate while the latter deflagrate. Their primary injury mechanisms are heat and blast effects. As mentioned earlier, the thermobaric cloud’s detonation creates extremely high temperatures, potentially vaporizing the human targets enveloped by the fireball. Because it utilizes all the atmospheric oxygen of a given area for combustion, a vacuum or ‘rarefaction’ is created which causes all the humans within its radius to die of suffocation, ruptured lungs, and burns. A prolonged high-pressure wave follows which obliterates the targets nearby. This is the most destructive stage and the damage inflicted by the shock wave increases when confined spaces like cave networks, bunkers, and buildings are targeted. The impulse is powerful enough to damage internal organs, disintegrate human tissues and rip through protective structures like bunkers. The final mechanism of injury involves suffocation through toxic smoke and incidental damage from falling debris. FAEs are also capable of eradicating vegetation in the affected area, showing that they can severely destroy natural resources. 

The immense destructive capacity of thermobaric weapons became evident in the 2017 airstrike in Achin, Afghanistan, known for the USA’s maiden use of the Massive Ordnance Air Blast (Also known as the “Mother Of All Bombs” or “MOAB”). The 21,000-pounds bomb that was dropped at the ISIS cave networks had a blast radius of 1 mile. Its blast overpressure and rarefaction reportedly “sucked the air out of the lungs” of the militants and collapsed the tunnel networks, killing around a hundred of them.

Therefore, thermobaric weapons severely destroy and erase human life and assets in the affected area. The near erasure of human life undoubtedly falls within “severe effects”. This is because “significant disruption of human life” is the standard required under the “severe effects” prong. Moreover, the effects may also be “widespread” if thermobaric weapons are used in large numbers. The affected area may thereby cover “several hundreds of kilometers” – the threshold of “widespread” according to the “Understandings”. Thus, while thermobaric weapons clearly have “severe effects” and would be banned per se under Article I, they can also meet the “widespread” threshold depending upon the manner and scale in which they are deployed.


Ironically, the two countries that started negotiations for the Convention presently house the most destructive thermobaric weapons. The preambular paragraphs of the Convention recognize the potential of science to open new possibilities for the modification of the environment. This treaty aimed to be futuristic in this regard and consider the advancements in the armament sector.

No review conference under the Convention has been convened since 1992. There is a lack of literature and judicial decisions on the applicability of the Convention to various modern warfare techniques. Therefore, there is a pressing need to bring to light the significance of ENMOD to regulate current warfare techniques. Even though the convention has deficiencies, the effective implementation of its current form can go a long way in preventing the use of such catastrophic weapons.

Print Friendly, PDF & Email
Featured, General, Technology
No Comments

Sorry, the comment form is closed at this time.