tanks and bulldozers in the two cities closest to mosul but they won't say why. cnn's senior international correspondent ar arwa damon is there on the outskirts. arwa? >> a sand storm has just swept in, adding another layer and difficulty of challenges to the current push around the town. this is the closest that iraqi forces have been to mosul since isis swept through and took it over more than two years ago and throughout the course of the day they have been coming across artillery fire, exchanging it, mortar fire, rocket fire and small arms fire exchanges as well. they don't know exactly how many isis fighters are here because the commander says isis is moving assets between the town and the city of mosul itself. we are less than a kilometer away from its outskirts but what isis has been doing and what we