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 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.

Each F-35 fighter jet contains roughly 900 pounds of rare earth materials, while submarines can require more than 9,000 pounds, the U.S. Department of Defense has concluded a stark reminder of how deeply integrated these elements have become in the machinery of modern defense.