The exception to this pattern is Anbar, an arid expanse bordering Syria and watered by the Euphrates river, where many towns are mainly in insurgent hands, despite periodic American assaults.

ECONOMIST: Iraq's constitution

"We all admire the beaver for the way it can turn a linear river into a lake with a dam, but the termites turning the desert into a pattern of oases that allow permanent life even in drought periods for hundreds of years - that's much more fascinating, " he told BBC News.

BBC: Termites 'engineer fairy circles'