(Photo : HAMZA AL-AJWEH/AFP via Getty Images)

Ukraine claims Russia fired phosphorus bombs in an airstrike on the besieged city of Bakhmut.

White phosphorus seems to be raining down on the city in a drone video provided by the Ukrainian military.

Although the deployment of white phosphorus weapons in residential areas is not illegal, it is a war crime. They cause flames to spread rapidly and be difficult to extinguish. Russia has previously been accused of using them.

Attack in Bakhmut City

The strategic relevance of Bakhmut has led Russia to spend months attempting to seize it. According to Western authorities, the attack has killed thousands of Moscow's forces.

Ukraine's defense ministry tweeted that "unoccupied areas of Bakhmut with incendiary ammunition" were the targets of the phosphorus assault. It was also reported by Kyiv's special forces command that Moscow's troops were still actively destroying the city.

The time frame of the claimed attack is unknown. However, Ukraine's published video, which was apparently shot by a surveillance drone, showed burning skyscrapers.

There was also footage of flames blazing on the ground and white clouds of phosphorus lighting up the night sky that was shared on social media.

In a report by BBC, the region seen in the defense ministry's video was determined to be the west of Bakhmut's city center, not far from a children's hospital. BBC analysis showed that incendiary bombs were employed in the assault, but it was unable to definitively prove that phosphorus was among them.

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Employing White Phosphorus

Since Russia's full-scale invasion of Ukraine last year, and especially during the first siege of Mariupol, the country has been repeatedly accused of employing white phosphorus.

Ukraine's president, Volodymyr Zelensky, said that white phosphorus had been used in the country's conflict last year, but Moscow has neither confirmed nor denied this.

White phosphorus is a wax-like material that, when exposed to oxygen, explodes into brilliant smoke plumes. The chemical is "notorious for the severity of the injuries it causes," according to Human Rights Watch (HRW).

Extreme burns may be inflicted on human flesh at temperatures of 800 degrees Celsius. In addition to being incredibly sticky and difficult to remove, it may reignite when bandages are taken off.

The employment of incendiary weapons (i.e., weapons intended to start fires) in civilian areas is prohibited under the Convention on Certain Conventional Weapons, which Russia has ratified. HRW, however, says that white phosphorus is not covered by the treaty since its main function is to "create a smokescreen to hide military operations."

Meanwhile, some experts argue that it should still be prohibited to employ such a weapon as an incendiary weapon in close proximity to humans. But despite having a population of 80,000 before the conflict, Bakhmut is now almost completely devoid of residents.

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