The Islamic State terror group claims it beheaded a Russian spy who had allegedly infiltrated its ranks. In a graphic video released Tuesday, the extremists are shown to behead the man who they describe as a captain in a Russian intelligence organization that spies on “terrorists.” The man’s name was given in Arabic, and in the video he is interrogated by a masked man, before he admits to traveling to Syria to spy on ISIS top military commander Omar al-Shishani, who was killed in a U.S. airstrike last year. “This idiot believed the promises of his state not to abandon him if he was captured,” the narrator says in the video, according to Reuters. Tens of thousands of foreign fighters from the former Soviet satellite states have traveled to Syria or Iraq to join up with ISIS. Tuesday is a national holiday in Russia, marking the anniversary of the 1945 defeat of Nazi Germany.