Days after a deadly Islamic State attack on a Russian concert hall in March, a man clad in military fatigues and a helmet appeared in an online video, celebrating the assault in which more than 140 people were killed.
"The Islamic State delivered a strong blow to Russia with a bloody attack, the fiercest that hit it in years," the man said in Arabic, according to the SITE Intelligence Group, an organisation that tracks and analyses such online content.
But the man in the video, which the Thomson Reuters Foundation was not able to view independently, was not real — he was created using artificial intelligence, according to SITE and other online researchers.