Russian-Ukrainian relations have spiralled since Moscow’s 2014 annexation of Crimea and the outbreak of a military conflict between Ukrainian government forces and Russian-backed separatists in eastern Ukraine. Russian investigators regularly open criminal cases against members of Ukrainian security forces into the shelling of property in eastern Ukraine.

Russia’s security services claimed to have disrupted an Islamic State member’s plot to assassinate an east Ukrainian rebel fighter on orders from Ukraine’s security apparatus.

The Federal Security Service (FSB) announced on Monday that it had detained Dagestani native Medjid Magomedov in western Russia’s Smolensk region on Sunday.

The FSB said Islamic State “emissaries” in Ukraine had introduced Magomedov to members of the Security Service of Ukraine (SBU) and the Right Sector, a far-right Ukrainian nationalist group banned in Russia, in early 2018.

There, the SBU and Right Sector allegedly tasked Magomedov with assassinating an unnamed Donetsk separatist leader residing in the Smolensk region.

The FSB said it had seized a handgun with a silencer and ammunition, as well as a homemade explosive device, when arresting Magomedov.

“Rustam [an alleged SBU member] offered to provide us with any weapon so that we could commit some terrorist acts in Russia together with the SBU,” Magomedov reportedly said in an interrogation video carried by the state-run Rossia 24 broadcaster.

The SBU has denied the reports, telling the Unn.com.ua news website: “It’s silly to comment on another Russian FSB fake.”

Islamic State is a terrorist organization banned in Russia.