You just knew that they'd taken a thing or two out of the viet cong playbook when it was reported that the insurgents were popping back up in the north of the city after it had already been swept by the marines.
I have a neighbor kid on the ground in Fallujah. So far no news is good news.
It was widely reported that Baghdad has an extensive tunnel network. It should be no surprise that other major cities do as well.
I'm sure that this was taken into consideration when Operation Phantom Fury was being planned.