ben wedeman live in us stan ball. looking back the fight for northern mosul took longer than expected. you've been on the ground. how might the fight for western mosul be different for these iraqi forces? >> reporter: for one thing the geography is different. in western mosul you have this old city. you have this market. the alleyways, the passages are much narrower than in the east. and, therefore, for instance, it's harder for tanks and armored personnel carriers to go through. we know that isis, for instance, has dug a network of tunnels and passageways and they're had lots of time to do that. they're also increasingly using a tactic we didn't see in the east. that is armed drones which they used to not only observe the iraqi forces but also attack them. the explosives charges they use