China's reported ban on rare earth metal exports to Japan underlined the risk of depending too much on one country for the crucial natural resource.
China, which controls more than 90 percent of the world's production of rare earth elements, reportedly halted exports as part of its diplomatic spat with Japan over the disputed Senkaku Islands.
While some rare earth shipments resumed Wednesday, China's clampdown forced Japanese firms to rethink their risk management strategies. Rare earth metals are crucial to producing computers, mobile phones, electric vehicles and other high-tech products.