The US has plenty of rare earths production capacity, we just don't mine them here because it is a dirty process and they are cheaper in China where they have fewer environmental regulations.
Most of US production capacity is merely mothballed, it could be spun up in less than a year - no doubt many companies that require rare earths have stockpiled months of supply against such a recurrence, given that they don't take up much space since such tiny quantities are needed for most products.
Trump is actually helping Biden by doing this now: China won't immediately retaliate because they will want to try to avoid escalating before they find out if Biden's administration will be more willing to deal. However, since Biden has said he wouldn't unilaterally undo any of the tariffs/sanctions because "why give up a bargaining chip" Trump is giving Biden more bargaining chips. Since the 'entity list' stuff is (at least in theory, hard to tell in Trump's corrupt administration where policymakers overrule career people all the time) coming from the intelligence community, how willing his administration will be to make deals will depend on what the intelligence people say. How real are these threats, versus being used as an excuse to go after China?
Biting the hand that feeds IT
