Should we negotiate with Isis? Here's what the experts think
Labour leadership contender Owen Smith has come under fire for his remarks that to solve the crises facing Iraq and Syria "we will need to get people round the table" - but was he right?
Smith's remarks have been called a "mistake" and criticised for legitimising Isis, but there are clearly questions about how to solve the conflict, and what groups of people we should be negotiating with in the region.
We spoke to some experts on negotiating strategies and Isis to see what they thought.
How do negotiations work?
The Northern Ireland peace process in the 1990s had to deal with how to bring politicians from both sides of the conflict to the table and leave behind the shadow of paramilitary activities.
Monica McWilliams, a former member of the Northern Ireland Assembly who had a seat at the multi-party negotiations, explained how the Good Friday Agreement worked.
"When we entered the talks in Northern Ireland we had about six different principles that we all had to agree upon. Clearly one of those was that we would adhere to and work towards resolving our difficulties through political means only and not by the use of any violent means," she said.
The principle of ceasefire is crucial to navigating successful negotiations - Sinn Fein were banned from negotiations for a year because the IRA had not reinstated its ceasefire.
McWilliams, who has more recently trained women to play a part in the Geneva peace talks on Syria, listed the key things to consider when negotiating with groups: "How representative are the group? How accountable are they? What are the structures you're negotiating with? And are they able to carry through on what will be agreed and what will be be delivered?"
Could we negotiate with Isis?
Bearing in mind the standards required for successful negotiations, McWilliams said: "I don't think Isis is at that stage.
"I don't think Isis is interested in being seen as representative and certainly not interested in being held to account - so I would be wary of who we would be negotiating with."
Andrew Hosken, a BBC senior correspondent and author of Empire Of Fear: Inside The Islamic State, agrees.
"This is a genocidal organisation that's committed crimes against humanity. It wants to conquer all of the so-called Muslim lands, and then afterwards they want to take over the rest of the world, and they've been very open about this, and subject it to their form of extreme Islam.
"It's very difficult for me to see what the negotiating position would be with Isis."
Jonathan Powell, who served as chief of staff to ex-PM Tony Blair between 1995 and 2007, and was instrumental in the Northern Ireland peace talks, has a different perspective.
He wrote in the Guardian last year that whilst military strategy is important in defeating Isis, so is dialogue. He said that even if Isis was defeated militarily, the idea behind it would still exist.
"I am not suggesting for a moment that we should sit down with Baghdadi (the leader of Isis) now and try to negotiate, even if he were prepared to sit down with us," he wrote.
"But we should do what we did in all previous conflicts: open a quiet channel that will allow us to begin negotiations once both sides have come to the realisation that there is no military solution."
Could we negotiate with anyone else in Iraq?
Hosken said one group that should be included in talks are the Sunni Muslims in Iraq.
The Sunnis, one of the two major denominations of Islam, the other being the Shias, made up large swathes of the Iraqi elite before the American invasion of Iraq in 2003.
They took top positions in Saddam Hussein's ruling Ba'ath Party, including senior posts in the military, the security services and other government jobs.
The Americans saw this as a problem - the majority of Iraq is populated by Shias. So, when they invaded, they implemented a policy of de-Ba'athification, which led to the sacking of thousands of Sunnis from these positions - widely considered one of the worst policy decisions made by the American government during this period.
When the Sunnis lost their jobs, many of them became insurgents, later taking their skills, tactics and anger to Isis.
"In terms of broader talks about the inclusion of the Sunnis in Iraq yes, people are talking about that and there are attempts to do that with the new government in Iraq already," said Hosken.
"It's something that clearly needs to happen because this was one of the big problems that fuelled the rise of Isis from 2010 to 2011. The ostracism of the Sunni and the feeling that they were being excluded helped Isis get back on its feet after almost being destroyed."
What about in Syria?
As well as Isis, other actors in Syria include the Free Syrian Army, the Al-Nusra Front, and President Assad's government forces.
Al-Nusra, a Sunni Islamist group with links to al Qaida, are not the natural bedfellows of the secular Free Syrian Army, but importantly neither group is Isis, and both groups are fighting Assad.
McWilliams, who has worked with Syrians, said: "When I talk to them they constantly ask me 'should we be talking to Al-Nusra?'" She said the two groups have joined forces in Aleppo to take back Assad-controlled territory, and that considering the unusual alliance, it "would make more sense to talk to them [Al-Nusra]" than Isis.
The West already broadly backs the Free Syrian Army, but negotiating with Al-Nusra would mean making sure the group fulfils the criteria for successful negotiations, said McWilliams. She added that would include demonstrating they care about human rights - something Al-Nusra are not famed for.
So what next?
In the controversial televised Labour leadership debate, Owen Smith said: "My view is that, ultimately, all solutions to these international crises do come about through dialogue, so eventually if we are to try to solve this all of the actors do need to be involved. But at the moment Isil [Isis] are clearly not interested in negotiating. At some point for us to resolve this, we will need to get people round the table."
It doesn't need saying that the situation is intense, volatile and dangerous - but whatever is decided happens next, it seems essential to have a rational debate and consider all the options.