Cameron says the UK could take action including launching airstrikes without approval from the Assad government as the regime has no legitimacy under international law:
President Assad is part of the problem, not part of the solution. Assad’s brutality gave credence to IS [Islamic State]
He says problems with governance in Iraq also led to the group’s rise there:
… There was an Iraqi government that was standing up for the Shias and not the Sunnis and the Kurds that again left a space for this poisonous organisation to fill
Asked whether a pragmatic deal with Assad is needed in the face of the greater ISIS threat:
In the past just simply saying ‘my enemy’s enemy is my friend’ has led to all sorts of moral quagmires and difficulties. Assad has been part of the creation of Islamic State rather than being part of its answer.