I was just watching a news report on the invasion and it showed regular (male) citizens lining up to receive weapons to defend the capital...
Anyone who knows anything about mounting a defense knows it's all about coordination and shifting of defensive lines to meet the offense....sadly, these untrained, uncoordinated defenders will succumb to an organized well coordinated offensive assault.
With all the firepower out there the untrained defenders will get in a few lucky shots but as we know the infrastructure will take a beating as the in-coming troops will destroy an entire building to oust one defender. This happened all the time in Iraq, an entire building would be destroyed to get one sniper....I've seen a building blown up only to see the sniper escaping via another route....(generally they didn't get far once they were spotted).