Importers could not import because they went broke jobs went out the window and he nationalized the oil fields and started them circling the old crapper.
You forgot the part where he kicked out the international workers who knew how to run the oil fields and keep the equipment in repair.. that was one of my favorite bits. Also the part where they slaughter and eat zoo animals because that is all there is left. Or paying govt troops in toilet paper.
I think he also fired the VZ oil field workers and replaced them with cronies. Maybe they went on strike.
I read about some guy who bought chicks and raised them to chickens for sale. The govt slapped price controls on him so he was losing money on each bird. He could not stay in business.