Dig +trace shows the recursive lookup (forwarders) used for your NS.
They almost always end up Arin and arpa. I've troubleshot some connection issues between different data centers and transit providers and found root hint oddities I just escalate to my supervisor
If the concern is that the US would somehow break the root servers and disrupt many trillions of dollars of trade I guess that is technically possible but probably unlikely given the amount of trade, tariffs, tax revenue that would impact would end anyone's political career and things would be reverted quickly in my opinion.
Who are "they" in this case?