What is behind the struggle for Iraq?

The borders of the modern Middle East are in large part a legacy of World War One, and were established by the colonial powers after the defeat and dismemberment of the Ottoman Empire.

Iraq is now coming under pressure on two fronts: an assault by Sunni insurgents, from the Islamic State in Iraq and the Levant (ISIS), and the continuing fighting and fragmentation of Syria.

Allan Little looks at the background to the region's tensions for BBC Newsnight.