The Ukrainian Armed Forces had already used thermite grenades, incendiary grenades with a temperature of over 2000°C dropped from a drone. However, a recent video shows a change in usage; the drone is equipped with a thermite charge that it activates but does not drop, preferring to spread thermite over an area rather than targeting a specific point. Once activated, the chemical reaction of these incendiary munitions reaches over 2000 degrees Celsius and continues to work even underwater or in a humid environment for several long minutes.
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Work of incendirary drones flying and dropping thermite grenades (Picture source:Ukrainian fighters )

On September 2nd, a new video of a drone attack in Ukraine was published on social media. However, it was not a suicide drone or a "bomber" drone: the Ukrainians have developed a new type of drone. The video (below) first shows the drone's flight path in FPV, but it is from 0:11 that the action becomes truly perceptible. Some thought it might be a flamethrower drone... but it's much worse! It's a drone equipped with a thermite grenade. This metallic mixture (often aluminum with a metal oxide) triggers a chemical reaction that reaches 2,000 to 2,500°C or even more. The molten metal then penetrates everything below, including metal plates, armor (depending on the thickness), wood, etc. Needless to say, the effect of a single "drop" of molten metal at 2,000 or 2,500°C on human skin is devastating. The reaction produces its own oxygen and thus works underwater!

The end of the video shows the underbrush on fire and the dilemma of the Russian soldiers there; staying in the trench means facing a fire, and for those not hit, moving is extremely dangerous because stepping on still-incandescent material (the chemical reaction can last several minutes) could easily melt a boot.

FPV view of Thermite drone attack ( Picture source:  Ukrainian Units ) 

This is not the first time a Ukrainian drone has used a thermite charge; on January 30, 2024, a Ukrainian "bomber" drone set fire to an abandoned Russian BTR-82A infantry fighting vehicle. That drone was equipped with small thermite charges specially developed to be dropped from drones. However, the use on September 2nd differs from this; the drone activates the thermite charge and keeps it in the air to spread it as widely as possible over the underbrush. Some might think this was a drone malfunction and an instant activation of the charge. But that is not the case, as the beginning of the video clearly shows the camera fixed on the treetops and not on a potential target. Even more, with such a high temperature, the drone would have melted immediately. This raises question, we haven't answers for moment: how did the Ukrainians manage to protect the drone from this intense heat? Did the drone return safely, or was it too damaged (you can see it flying away once the charge is extinguished)? Was the charge hanging at a safe distance from the drone?

The thermite mixture, weighing between 500 and 530 grams, is contained in an aluminum pipe, along with a circuit board and an ignition system, bringing the total weight to about 700 grams. Once triggered, it reacts in 3 to 4 seconds, causing active combustion for approximately 2 minutes, during which the temperature can reach up to 2500°C. After this phase, the molten metal continues to burn. This device is designed to set fire to enemy positions, trenches, lightly armored vehicles, and automotive equipment. When it strikes a horizontal part of a lightly armored vehicle, it can penetrate it. It works more reliably when dropped from low altitudes. The cost of each unit is 450 UAH, or about 12 USD

In the context of the Ukraine conflict, incendiary weapons have been widely used, sometimes even in civilian areas. However, as mentioned at the end of the article, international law does not prohibit the use of these weapons as long as civilians and protected areas are not targeted. However, the restrictions are lifted if the weapon's purpose is not to set fire but to illuminate. This is why several uses of thermite, on both the Russian and Ukrainian sides, have been reported during the conflict.

This creates very impressive images of the Russian Armed Forces, who have already used thermite against the Ukrainians. They used 9M22S rockets (122 mm) fired from BM-21 Grad multiple rocket launchers. Each of these rockets contains 180 small charges that are then ejected and ignited above the target. These shots are visually very impressive and are based on the principle of flares. However, they ignite small fires as soon as they hit the ground. These strikes are minimally destructive but visually striking. They were carried out with the aim of creating a buzz and, above all, worrying the opposing forces. These luminous attacks therefore play on psychological and communicative effects rather than solely on destructive power.

Thermite shelling over the village of Ozerne in the Artyomovsk/ Bakhmut district of the Donetsk region, september 2022 ( Picture source: Russian drones observers)

Thermite grenades are often used outside this conflict; during the withdrawal of the last American troops from Kabul Airport (Afghanistan), some high-tech systems had to remain operational until the last moments, forcing Special Forces to destroy them before boarding the last planes. This was notably the case for two Centurion systems, offering C-RAM (Counter-Rocket Artillery Mortar) capability at the airport. It is certain that these two systems were destroyed, and given their high technological value, many experts believe that thermite grenades were used. In France, thermite grenades are used in Guyana to destroy equipment seized from illegal gold mining sites. Due to their high light output, these grenades are often visible in reports on the Forces deployed in this area.

The law of war, also known as international humanitarian law (IHL), is a set of rules aimed at limiting the effects of armed conflicts for humanitarian reasons. It protects those who do not directly participate in hostilities, such as civilians, medical personnel, and prisoners of war, and limits the means and methods of warfare that belligerents can use.

Regarding the use of incendiary weapons, these are specifically designed to ignite objects or cause burns by fire using flammable substances such as napalm, white phosphorus, or other chemical compounds.

Protocol III of the Convention on Certain Conventional Weapons (CCW), adopted in 1980, regulates the use of incendiary weapons. This protocol prohibits the use of incendiary weapons against civilians and in areas where there are concentrations of civilians. It also imposes restrictions on the use of such weapons against military objectives located near civilian areas to minimize collateral damage.

However, there are ongoing discussions about the effectiveness and adequacy of these regulations, given that some states continue to use incendiary weapons in controversial conditions. White phosphorus, for example, while it has legitimate military applications, is often criticized for its use against targets where civilians may be affected.

Presentation of FPV mounted  thermite grenade  ( Picture source : Ukrainian FPV units)

This attack by a drone carrying thermite charges is the first of its kind. Visually striking and effective, the attack remains relatively small in scale, making it a minor element strategically as it is not widely usable; such an operation is still dangerous for foot soldiers.

However, it is visually impactful because the drone passes very quietly, and everything ignites in its path. Moreover, the published images show that the environment also catches fire, making the attack even more effective. Technically, it is particularly effective, but strategically, it is difficult to see any effect other than psychological and media-related, especially since the law of war does not prohibit but also does not encourage the use of incendiary weapons for offensive purposes.