roland buerk reports from tokyo. >> for decades, japan's factories have drven its economy, supplying the world with electronics and cars. but as the industrial machine is looking vulnerable, high-tech manufacturing requires rare earth and china has a near monopoly on supply. >> this is original rare earth ore -- >> at tokyo's biggest trading house, they've seen shipments dry up suspects a territorial dispute between china and japan began. >> already one month of nearly two months will pass, and not yet coming even the one kilo. >> so japan is looking for its own rare earth. once people send their used computers for recycling to be more green. now what's inside is needed so badly, they call this urban mining. this place works on the principle that yesterday's must have is today's obsolete junk. look at this. it's a sega mega drive. not that long ago on the top of every kid's christmas wish list. these are all computer monitors. they take up too much room on people's desks now. these are old p.c.'s. who wants an electric typewriter these days? let alone a cassette deck. but inside all