The extremist Islamic group known as the Islamic State - also called ISIS or ISIL - and groups connected with it - are believed to have killed thousands of civilians in Iraq and Syria, as well as having executed hundreds of Syrian and Iraqi security forces. To a lay person, this would seem like a clear-cut case of genocide. But is it genocide under international law? And if so, what can or should be done about it?
In 2014 alone, the United Nations says Islamic State militants systematically killed and injured more than 24,000 civilians, enslaved women, recruited children, and conducted a brutal campaign of violence across Syria and Iraq.
Horrific on-line images of beheadings, crucifixions and mass executions of soldiers - as well as reports of torture - are testimony to the group's code of terror.
Earlier this year, the Sunni extremist group targeted ethnic Iraqi Yazidis, killing the men and publicly defending the enslavement of the women. But they have also targeted other Muslims, especially Shia.
U.N. Human Rights Commissioner Zeid Ra’ad al-Hussein says the Islamic State is out to destroy anyone who does not agree with them.
"Alternative view-points - indeed, any form of individual thought outside of their closed, unyielding logic - is rejected by them. Those dissenting humans must be murdered, their memory, culture, every shred of their existence, destroyed," said al-Hussein.
The U.N. says the actions of the Islamic State have met three out of the five criteria that define genocide under the international Genocide Convention.
U.S. Undersecretary of State Richard Stengel says the group is "ruthless."
“They are a genocidal organization, I would say, in a sense that they are determined to wipe out whole groups of people indiscriminately, innocent people; so, their ideology I believe is genocidal and what they are doing is just despicable in every way,” he said.
The Genocide Convention says anyone guilty of the crime "shall be punished" -- but it speaks primarily of legal action. Where the Islamic State is concerned, an international coalition has been conducting air strikes against the group since August, and is supporting Iraqi and Kurdish forces battling the extremists on the ground.
The question now is whether that will be enough, says Daniel Serwer of the Johns Hopkins School of Advanced International Studies.
“What we are doing now, seems to me, has had a certain effectiveness in blocking the expansion of the Islamic State, it’s protected some populations that would otherwise have been at risk, but it’s doing nothing yet to really collapse the Islamic State. We’re not. We may be degrading it, but we’re not defeating it as yet,” he said.
Meanwhile, Islamic State militants have captured large areas of Syria and Iraq, declaring the region a caliphate that all other Muslims should follow.