Beijing has approved more export licenses for the critical minerals and magnets in recent days, but supplies remain scarce and factories in the West are running out.

China mines about 70% of the world's rare earths but has a virtual monopoly on refining and processing. Even if the pace of export approvals quickens as Trump suggested, the new system gives Beijing unprecedented glimpses of how companies in a supply chain deploy the rare earths it processes, European and U.S. executives have warned.

China views its rare earths as a national security issue, not a trade one, and that’s why Beijing is unlikely to loosen controls any time soon, experts say.