It has been said that other countries, including US, in fact have more rare earth deposits. If they choose to relax environmental laws and disregard patents held by Chinese corporations, more rare earth would be produced.
A global strategic bottleneck in China for these things doesn't require patent or environmental law violations, it just requires us to pay more for them. For a critically strategic resource like this, the US should ensure a consistent supply chain independent of geopolitical concerns with China. And if China were to cut off supply then concern for their patents goes out the window too.