Basically, the US never stopped spying on Germany after WW2. I'd guess they kept upgrading their hardware during the cold war, and apparently never stopped after its end.
Also, the occupation authorities were instrumental in establishing the German intelligence service from the get-go, liberally making use of the existing NS personnel (Wikipedia[1] lists Reinhard Gehlen, Klaus Barbie, Alois Brunner, Wilhelm Krichbaum, Franz Rademacher, Walther Rauff, Konrad Fiebig, Franz Alfred Six as prominent examples).
[1] http://de.wikipedia.org/wiki/Bundesnachrichtendienst#Geschic...