MP Materials has announced plans to expand rare earth mining and processing operations as Washington seeks to end its dependence on Chinese supplies.

MP Materials unveiled a multibillion-dollar deal with the U.S. government on Thursday to boost output of rare earth magnets and help loosen China's grip on the materials used to build weapons, electric vehicles and many electronics.

The Defense Department is buying $400 million of stock in rare-earth mining company MP Materials as it seeks to boost domestic sources of the critical minerals.