Right at the end of the article is an interesting statement:

  The report said the NSA had equipped the listening station 
  in Bad Aibling with sophisticated technical equipment. A 
  number of NSA personnel are believed to work there together 
  with some 120 BND personnel.

The point here is that NSA personnel are on secondment or implants to use another term. Having implants encourages complacency. You end up with scenarios like:

   Bob (NSA): hey Klaus, can you add these new selectors to the filters please?

   Klaus (BND): Ja, when do you want that? Tomorrow ok? I'll get Alice to run them tomorrow. You still want to come to the summer party this weekend?

Familiarity in security scenarios is dangerous. Implants breed familiarity.