The US can and does produce rare earth elements:

https://en.wikipedia.org/wiki/Mountain_Pass_Rare_Earth_Mine

The Mountain Pass Rare Earth Mine and Processing Facility, owned by MP Materials, is an open-pit mine of rare-earth elements on the south flank of the Clark Mountain Range in California, 53 miles (85 km) southwest of Las Vegas, Nevada. In 2020 the mine supplied 15.8% of the world's rare-earth production. It is the only rare-earth mining and processing facility in the United States. It is the largest single known deposit of such minerals.

Look at the history section to see how this mine initially dominated rare earth element production, then shut down due to low price competition, then reopened, then shut down due to low prices, then reopened.

The total addressable market for rare earth elements is small in dollar and tonnage terms, but opening mines and processing plants is expensive. One big new mine could tank the global market price.

The US used to maintain large stockpiles of many mineral resources for defense purposes, but mostly stopped in the 1990s after the end of the Cold War. The pendulum may be swinging the other way now. The Mountain Pass mine received DoD grants in 2022 and 2023 to support continued operation, regardless of open market prices.