KYIV, Ukraine (AP) — Ukraine launched an investigation Wednesday into a gruesome video that purportedly shows the beheading of a Ukrainian soldier, in the latest accusation of atrocities said to have been committed by Russia since it invaded in February 2022.

The video spread quickly online and drew outrage from officials in Kyiv, including President Volodymyr Zelenskyy, as well as international organizations. The Kremlin called the footage “horrible” but said it needed to be verified.

The Associated Press was not able to independently verify the authenticity of the video or the circumstances of where and when it was shot. The AP is not distributing the video or using frame grabs due to its extremely graphic nature.

Meanwhile, a Russian defence official claimed that fighters from Russia’s paramilitary Wagner group have seized three districts of Bakhmut, the embattled city that for months has been the focus of Moscow’s grinding campaign in the east.

The video circulating online appears to show a man in green fatigues wearing a yellow armband, typically donned by Ukrainian fighters. His screams are heard before another man in camouflage uses a knife to decapitate him.

A third man holds up a flak jacket apparently belonging to the man being beheaded. All three men speak in Russian.

Since Russia’s forces invaded on February 24, 2022, they have committed widespread abuses and alleged war crimes, according to the United Nations, rights groups and reporting by The Associated Press. Ukraine has repeatedly accused Russia of targeting apartment buildings and other civilian structures and equipment in its strikes, and images of hundreds of dead civilians in the streets and in mass graves in Bucha after Russian forces withdrew from the city have horrified the world.

The International Criminal Court has issued an arrest warrant for Russian President Vladimir Putin for war crimes, accusing him of personal responsibility for the abductions of children from Ukraine.

The Kremlin denies it has committed war crimes or that it has targeted civilians.

Ukrainian troops have also been accused of abuses, and last year Kyiv said it would investigate video circulating online that Moscow alleged showed Ukrainian forces killing Russian troops who may have been trying to surrender.

Zelenksyy said the violence in the latest video would not be forgotten, and that Russian forces would be held responsible.