>> narrator: marouf would lead a new movement, called the syrian revolutionary front, to fight against the jihadists. >> (translated): we're ready to fight every group that behaves like the regime. and if a group wants to use weapons against us and fight us and their goal is to steal the syrian revolution, we will not hesitate to fight back. >> narrator: a young fighter named hazem, who was a lieutenant in assad's army before defecting, has signed up his rebel battalion to the new syrian revolutionary front. he shows muhammad what they are up against. >> (translated): we're driving along these farm roads to avoid being attacked by the jihadists. the jihadists are more ruthless than assad's regime. they attack villages with artillery and shells. in that village they just killed 15 civilians, including women and children. they use mines and car bombs as if we are their main enemy. but they are the enemy of the revolution and for syria as a whole. >> narrator: the most radical of the jihadist factions to turn against the other rebels is the islamic state of iraq and syria: isis. (machine