Rainer Rupp (born September 21, 1945 in Saarlouis, Germany) is a former top spy who worked under the codenames Mosel and later Topaz for the East German intelligence service HVA (General Reconnaissance Administration) in the NATO headquarters in Brussels from 1977 until 1989, releasing documents of the highest importance (Cosmic Top Secret) to the Eastern Bloc.
He rose quickly in the ranks and provided photographs of some 10,000 pages to his controllers, including the precise location plans for the deployment of cruise missiles and Pershing II missiles in Western Europe, as well as the central MC 161 document which summarized the NATO strategy as well as NATO's analysis of the Warsaw Pact and its intentions.
"[citation needed] NATO did not have any knowledge of the existence of Topaz until GDR officer Heinz Busch defected in 1990.
With the help of the Rosenholz files that had fallen into the hands of the CIA after the dissolution of the GDR, Rupp was caught in 1993, while on vacation in Germany.
Rupp became a member of the PDS and served temporarily as an advisor in regard to issues of security and foreign policy; he quit the party, however, in 2003.