A month after Islamic State extremists shocked the nation with the cold-blooded murder of two Japanese hostages, the frame of its threat is now becoming clear.

Shortly after the execution of Kenji Goto, the group raised the stakes in unspeakable online violent imagery, showing it burning a Jordanian pilot to death and beheading 21 Coptic Christians in Libya.

Most recently it was reported to have abducted scores of Assyrian Christians, including women and children, in northeastern Syria.