free markets
Some illogical bloviating going on here. The whole point of new rare earth mines opening (also in Australia) is so that no one country controls access or availability. Since a huge amount of what the US (and the rest of the western world) imports is made in China, there is no reason not to export to them. But Japan is the next biggest user--again mostly for products that are exported--and this was the problem when China restricted exports (for whatever reasons). As noted in the article Japan will be taking a very large fraction of the US output.
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It is of course ridiculous to imagine that China wants conflict with the US. It is in fact the exact opposite: there are plenty of far-right American war-mongers who see that promoting this notion is the way to keep the MIC rolling along, consuming trillions of dollars of your deficit budget.