Moscow shooting: What is IS-K and why would it target Russia?
Islamic State Khorasan (IS-K) has taken credit for attacks by other terror networks in the past, but it is almost certainly behind the deadly assault in Russia, though nothing is impossible. Many people presumed Islamic State (IS) had been neutered, but it has been growing in strength in recent years, particularly IS-K. Khorasan is an ancient term referring to regions of Turkmenistan, Afghanistan and Iran.