U1 FBI informant = Carter Page
https:// theconservativetreehouse.com/2018/02/05/in-march-2016-carter-page-was-an-fbi-employee-in-october-2016-fbi-told-fisa-court-hes-a-spy/
Carter Page was working for FBI before FISA warrant. They used his undercover work product as a proof that he was a Russian spy to get the FISA warrant. ~ CTH