Tor has been analyzed extensively by cryptographers and security researchers; there is literally a mountain of published research about it.
And that research says that if an entry node and an exit node are both under control of an adversary, then that adversary can deannonymize the target.
I don't know enough about it, but I know that deannonymizing someone is a matter of resources, not a matter of ability. And the USG has a lot of resources.