Darfur: Why are Sudan's Janjaweed on the attack again?

A major city in Sudan's Darfur region has been under fierce attack - days after thousands of people arrived there seeking safety after their own town was set ablaze by horse-riding Arab militias known as Janjaweed.

"For the first time in Geneina's history, the hospital has been completely evacuated. All health institutions in the city are closed," the co…