Jeremy Corbyn has said there must be a "route through" to Islamic State (IS) to help bring about an end to the conflict in Syria.
The Labour leader said governments in the region were already "in touch" with IS, which he compared to the "back channel" that existed between the British government and the IRA during the Troubles in Northern Ireland.
"The British government maintained a channel to the IRA all through the Troubles. I don't condemn them for that, I don't condemn them for keeping a back channel to the Taliban," he told BBC1's The Andrew Marr Show.
"There has to be a route through somewhere. A lot of the commanders in Isil (another name for IS) - particularly in Iraq, but also in Syria - are actually former officers in the Iraqi army.
"Dialogue is perhaps the wrong word to use, but there has to be some understanding of where their strong points are, where their weak points are, and how we can challenge their ideology.
"I believe that the neighbouring governments in the region are in touch. Look at the way in which there has been some degree at times of prisoner exchange, hostage exchange - things like that. We have got to bring about a political solution in Syria."