Britain must build bridges with Syrian President Bashar Assad to tackle the threat from Islamic State (IS) extremists, the former head of the Army has said.
Lord Dannatt suggested the West needed to recognise that it had misread the situation in Syria, where it has called for Assad to give up power, and seek the regime's assistance in combating the group.
Speaking on the BBC Radio 4 Today programme, the peer said IS had to be "opposed, confronted and defeated" in both Iraq and Syria.
"The Syrian dimension has got to be addressed. You cannot deal with half a problem," he said.
"The old saying my 'enemy's enemy is my friend' has begun to have some resonance with our relationship with Iran.
"I think it's going to have to have some resonance with our relationship with Assad."
A British family have told ITV News of their devastation after discovering a close relative is fighting with the Islamic State in Iraq.
A French journalist who was held hostage with James Foley in Syria has told ITV News it was "devastating" to see his murder.