China has cut Japan off from several heavy rare earths and other materials for at least four months, coinciding with a dispute between the two countries over Taiwan, suggesting Beijing is using its control over critical minerals ​as diplomatic leverage. Japan is the largest rare earth magnet maker outside China but like the rest of ‌the world is overwhelmingly dependent on Beijing for imports of certain so-called heavy rare earths used in magnet-making, aerospace and defence, as well as gallium, a minor metal vital for chip-making. Since December, Chinese exports of rare earth minerals like dysprosium, terbium and yttrium oxide, as well as speciality ​metal gallium, to Japan have stopped except for a few tiny shipments of yttrium, Chinese customs data shows.

Full report : China squeezes Japan over rare earths in repeat of 2010 showdown.