builds that have families and the air force strikes these buildings killing them and everyone in the house. >> now, ivan, both iraqi and u.s. military officials say that this isn't going to slow down the operation despite the calls from some local provencial leaders to do so. the u.s. military also reiterating that their goal is zero civilian casualties. we know that is nearly impossible. >> that's been one of the enormous challenges of trying to uproot isis from mosul. it is a densely populated city with hundreds of thousands of civilians there. you can't just simply flatten the place, because you will hurt so many innocent people. it is hard to imagine a potentially worse or more horrific situation for the civilians trapped in the middle of this awful and grinding urban conflict, ian.