Is the battle against Islamist terror unwinnable?

Militants from the Nigerian group Boko Haram have attacked a school in north-eastern Nigeria, with at least 29 students reported killed - some of whom were burned, while others had their throats cut, according to reports. Scores of people were killed in two attacks last week. In one incident, militants destroyed a whole village and shot terrified residents as they tried to escape. What is driving this campaign of terror from Islamist militants? And is it ever possible to stop them?