ELEANOR HALL: To the latest horrific video from Islamic State militants that's threatening to draw Egypt into a broader regional conflict.
The video shows IS militants who are destabilising Libya beheading 21 Coptic Christians.
Egypt's president is now threatening to intervene in neighbouring Libya, saying he reserves the right to respond to the killings of Egyptian hostages in what he termed a "suitable way".
Barney Porter has the latest.
BARNEY PORTER: The Coptic Christians had been kidnapped last month in two separate incidents.
Abanoub Ishaq was a friend of some of the hostages; he now counts himself as one of the lucky ones.
ABANOUB ISHAQ (translated): I was in a different room. After about 10 minutes they knocked on the room next door and took those who were inside and left. Then they started to bang on our door but we refused to open it.
BARNEY PORTER: Professor Robert Bowker is with the Centre for Arab and Islamic Studies at ANU.
He was Australia's ambassador to Egypt between 2005 and 2008.
ROBERT BOWKER: The group is part of a franchising arrangement that Islamic State has adopted as a means of raising its profile across the region, but also there's a certain imitation of the practices of the Islamic State in Syria and Iraq, which the group in Libya is clearly pursuing.
We've seen something similar also in the behaviour of the franchise in the Sinai, which now calls itself the Sinai Province.
But the beheadings, the use of social media, and the horrific commentary that goes with these activities are very much a part of a standard IS model.
BARNEY PORTER: Recently IS claimed responsibility for an attack on a five star hotel in Tripoli. Does this latest incidence suggest the group's hoping to play a more prominent role in Libya's internal political chaos?
ROBERT BOWKER: I think the latest incident affecting the cops is another barbaric example of the intention of IS to place its own brand in front of Arab audiences and western audiences and in that sense it does have some resemblance to what IS was trying to achieve in its attack on the Corinthia hotel.
FAWAZ GERGES: It's a sectarian massacrer, I think, to simply summarise what happens is that IS is trying to really fuel sectarian hatred.
BARNEY PORTER: Fawaz Gerges is the chair of Middle Eastern Studies at the London School of Economics.
He's told al Jazeera they were killed simply because they were Christians.
FAWAZ GERGES: IS now, or the so called Islamic State, is spreading near and far. So you have now in Iraq, in Syria, in Libya, in Yemen, in North Africa, as far as Afghanistan.
It's a social epidemic. What happened really today is basically a sectarian bloodbath; it's a massacre.
BARNEY PORTER: Libya has been a fractured nation since the fall of Muammar Gaddafi in 2011, with two rival governments now claiming to lead a people split down regional, tribal and social lines.
Within hours of confirmation of the killings, the Egyptian president, Abdel Fattah al-Sisi, appeared on national television to warn that Egypt would respond appropriately and in its own time.
After an emergency meeting of his top security body, he's offered to evacuate all Egyptians from Libya, raising immediate speculation that Egypt could attack IS groups inside the country.
ABDEL FATTAH AL-SISI (translated): Egypt does not only defend itself but the whole region, Egypt will react in the right time, we will keep following the situation and we will discuss how we will react in due time.
BARNEY PORTER: Fawaz Gerges says he would not be surprised to see Egypt becoming militarily involved in Libya, using the death of the Coptic Christians as a pretext, but he says there would be regional implications.
FAWAZ GERGES: Look what's happening now, regional powers are being sucked in.
So you have now in Yemen you can imagine Gulf States intervening in Yemen as a result of Yemen also fracturing.
In Libya I could easily imagine Egypt intervening in Libya. In Iraq as well, the Jordanians are being sucked in.
So ISIS has managed, not only to really commit great massacres, but also to really trigger a region wide conflict with major consequences for regional security and global security as well.
ELEANOR HALL: That's professor Fawaz Gerges, from the London School of Economics, ending that report by Barney Porter.