"Picture any large metropolitan city on the U.S. East Coast — dense, older cities with smaller streets. And then picture having to eradicate all crime and any enemy force in there," says Brig. Gen. Scott Efflandt."It requires street by street, house by house, room by room operation," he said. "There's no quick way to do it. You have to walk, you have to climb stairs, you have to open doors and then repeat the process again and again and again and then when you're doing that you have to leave someone behind to guard the area you just went through. "That's without U.S. troops on the frontlines.