During the Cold War system conflict, both sides operated not only with their respective intelligence services, but also through intermediate associations. The Western intelligence services mobilized a wide range of anti-Communist “front organizations” from the right wing of the political spectrum, but also radical leftist fringe groups. For example, the Group of International Socialists (GIS), which reemerged its their council-communist origins in the Weimar Republic, operated across the sector border of West Berlin and within the GDR in order to destabilize the totalitarian regime. This occurred with the support of US agencies. However, due to the abduction of GIS’ most important activist, Alfred Weiland, the Eastern intelligence services were able to infiltrate the GIS’ cross-zonal connections, which led to the destruction of the oppositional networks within the GDR. The article highlights the special role that Weiland played as a confidant of the US intelligence agencies.