Read all about it, here.
The article from WaPo is confused about the US Fleet. The 7th Fleet is Japan-based. The Italy-based Fleet is the 6th, not the 7th.
"Navy officials had previously recommended reactivating the fleet as part of broader force structure reviews following last year's deadly row of collisions among ships at the Japan-based 7th Fleet. In a separate statement, Richardson invoked Defense Secretary Jim Mattis' national defense strategy as key guidance to reestablish the fleet, which will extend halfway across the Atlantic until it meets the area of responsibility for Italy-based 7th Fleet."
