Small groups of Syrians are hunting down Islamic State fighters in one of their main strongholds in eastern Syria in a new guerrilla campaign that has emerged as a response to the Islamists' growing brutality. The main aim is to generate fear in Islamic State's ranks, said the head of "White Shroud" - a group that says it has killed more than 100 Islamic State fighters in attacks in Deir al-Zor province in recent months