When the Federation of German Scientists (VDW) was founded as the West German section of Pugwash in the late 1950s, several high-profile scientists from the Max Planck Society (MPG), especially nuclear physicists, were involved. Well into the 1980s, institutional links existed between the MPG, the Federal Republic’s most distinguished scientific research institution, and Pugwash, the transnational peace activist network that was set up in 1957 in the eponymous Nova Scotia village following the Russell-Einstein Manifesto. In the beginning, the two organisations’ relationship was maintained primarily by the physicist and philosopher Carl Friedrich von Weizsäcker. However, it was difficult right from the start, and the distance between them grew during the rise of détente in the 1970s, when the scientific flagship MPG was deployed more and more frequently in matters of foreign cultural policy, not only for the FRG but for the western alliance as a whole. This contribution explores the resources and the risks of transnational political engagement – not only as the individual strategies of top-ranking researchers, but also in terms of policy deliberations within a leading scientific organization at one of the Cold War’s sharpest divisions: the front line between two Germanys.