I reckon they mean Fire Control-man 3rd class. An FC3 (SS) isn't likely to know a whole lot the Russians wouldn't already know. That said, I wonder why the Russians would want to know how to launch stuff from submarines?
Maybe the Russians REALLY want to know if they can open a channel to start selling all their out-dated military garbage laying around so they can raise some extra cash?
But why go to the U.S.?They can get for FREE so many "secrets" about the U.S. from anyone in the U.N. these days! And get a few million free oil receipts too for their labor!