People's Republic of China (the ChiComs) cut off export of some "rare earth" materials to the US.
The AOSHQ's Super-Nerd IT directorette Pixy Misa puts it into perspective.
There are a few things to note here:
...First, of course, it makes little sense to make a totalitarian fascist dystopia your sole supplier of anything.
Second, rare earth elements are not rare. What they are is messy and annoying to extract and refine, a fact that China used to take over the market. Australia, Brazil, Canada, and, yes, the United States all have significant mineral reserves available. And studies suggest that a square mile of seafloor mud is enough to provide the entire world with these metals for a year.
Third, China of course does this kind of thing all the time, and has restricted or outright banned sales of rare earth elements to other countries before.
Fourth, and perhaps most interesting, China now only produces 10% of its own rare earth resources. The same problem with them being messy and annoying to extract led it to move production to illegal mining camps operating in Burma, bypassing what passes for the government and working with local militias....
Do not doubt her. http://ace.mu.nu/archives/414339.php
That "messy and annoying" extraction/refining problem--combined with the EPA and various other pieces of The Regulatory and Strangling Octopus at State and Federal levels--is what chased rare-earth prospectors out of the US.
Maybe Trump could do something about that...........
