Putting every house, storage building, moving vehicle or hole in the ground from which you take fire "under siege" would seem to be a good way to tie up an entire army very quickly, without accomplishing anything.

The US/UK forces are not exactly functioning as an "occupying army." Occupation and what they now like to call "nation building" begins when active combat has not ended. It has not, regardless of what Mr. Bush said (in one of his stupider comments), and it does not appear that either we or the Iraqis will see any spitshined boots and MP brassards anytime in the immediate future.