Defense Primer: Acquiring Specialty Metals, Rare Earth Magnets, and Tungsten [Updated January 30, 2020] [open pdf - 452KB]
From the Document: "Some metals (such as titanium and tungsten) and metal alloys, as well as strong permanent magnets known as rare earth magnets, are critical to U.S. Department of Defense (DOD) operations. These materials are frequently integrated into components (e.g., integrated circuits, electrical wiring, or optoelectronic devices) or structures (e.g., aircraft fuselages or ship hulls) of the military platforms and weapon systems that enable warfighting capabilities."
CRS In Focus, IF11226
Congressional Research Service: https://crsreports.congress.gov/