The GDR Ministry for State Security (MfS) remained a "servant of two masters" even after its formal equality with the Soviet secret service KGB in 1958. It continued to act both as a "shield and sword" for the ruling state party, the SED, and as a service provider for the Soviet "friends". In fact, it was not equality but informal submission of the MfS that shaped the cooperation with the KGB. It is hardly known that the KGB not only used the possibilities and capacities of the Stasi, but also those of the People's Police and the Ministry of the Interior to strengthen and expand its agent networks for espionage in the West or to collect information in the GDR - and this often without the knowledge of the MfS. The KGB viewed the GDR as its operational playground, in which it alone determined the laws of action. This volume illustrates the different facets of the KGB presence in the GDR on the basis of newly evaluated documents with many concrete examples.