It looks like fireworks raining down from the sky in Donetsk, Ukraine. Although we don’t know exactly what the fireworks-like blast is, researchers have suggested a chemical called thermite could be to blame.
This is not the first time Russia has been accused of using thermite or similar incendiary projectiles, so it’s worth understanding what thermite is, how it can be used and the human rights implications.
“The use of force in armed conflict must be only directed at legitimate military objects or persons, and in this case it appears that the Russian military is purposefully and unlawfully attacking civilians and civilian targets,” says Dr Lauren Sanders, a law researcher specialising in international humanitarian law at the University of Queensland.
“This has been a problem documented since the commencement of their so-called special military operation in Ukraine.”
Thermite is a mixture that can be used as an incendiary weapon, in the same way as the more well-known napalm and white phosphorus. These weapons are incredibly hot and are designed to start fires, destroy equipment, and are particularly damaging to flesh.
What is thermite?
Thermite is a substance made up of a metal such as aluminium and iron oxide.
In a reaction called the Goldschmidt process, a spark causes the metal – aluminium, in our example – to bond with the oxygen. This becomes aluminium oxide and releases a very large amount of heat.
“In the case of a bomb, you’d need to start off with some normal explosives that would generate enough heat to get the thing heated up. And then it goes on its own devices,” says chemist Professor Ian Rae from the University of Melbourne.
Thermite’s uses aren’t only as a weapon – because the materials are stable at room temperature and the reaction produces such high temperatures, it has been used to join railway tracks, and melt metal.
“It’s the kind of thing people do for chemical open day displays to show off a bit,” says Rae.
“The products are molten. Aluminium oxide isn’t stable at that temperature, but the iron is molten and so you can use that molten iron to join things together.
“You’ve got to stand well back.”
How are incendiary weapons used in conflict?
Incendiary weapons like thermite and white phosphorus can be used to mark, signal, penetrate metal or create smoke screens. This ‘multipurpose use’ means it’s not regulated by the current protocols surrounding incendiary weapons.
“These sorts of weapons can be used for legitimate military purposes,” says Sanders. “White phosphorous is often lawfully used for illuminating target areas before striking with other munitions, for example.”
“When it is being used as a weapon to cause burning effects on human targets, in and of itself, however, it breaches the laws of armed conflict.”
What does it do to humans and the environment?
The reaction can reach up to 2,500°C, and no matter its intended purpose, incendiary weapons like thermite can still produce horrific injuries.
“Incendiary weapons produce heat and fire, inflicting excruciatingly painful burns on civilians and soldiers alike,” Human Rights Watch wrote in a 2016 report on incendiary weapons.
“Those who survive endure injuries that are difficult to treat and can lead to severe permanent disfigurement and long-term psychological harm. Fires started by incendiary weapons can be difficult to extinguish and can destroy civilian objects and infrastructure.”
While other devices reported to be used by Russian forces like thermobaric weapons employ the air around them as fuel, thermite uses the metal oxide as the oxygen fuel source, meaning there’s very few ways to stop the process until the reaction is exhausted.
Although thermite can also melt buildings and cause fires due to the heat, once the reaction has finished the two products – iron and aluminium oxide – are relatively harmless.
Is this legal?
Although the law is a little wobbly around these incendiary weapons, it is not when talking about how they’re used.
“In terms of incendiary weapons there’s no prohibition on these weapons per se, that is there is no treaty obligation to these weapons out right,” says Sanders.
“However, the manner in which these weapons are being used is arguably unlawful. There are a number of reasons for this unlawful use – the first and foremost being that the weapons are being used to cause unnecessary suffering to the intended targets.
“This is one of the core principles of international humanitarian law, which requires that only the minimum force necessary to achieve the military aim may be used and that weapons can’t be used for cruelty’s sake.”
Jacinta Bowler is a Cosmos science journalist and podcaster who has written about far-flung exoplanets, terrifying superbugs and everything in between. They have written articles for ABC, SBS, ScienceAlert and Pedestrian.
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