The pipe embargo marked the end of an era for Bonn. It was one of the last explicit uses of negative economic leverage by Adenauer, whose “policy of strength” had achieved no concessions from the Russians on the central issues of reunification, Berlin, or the restoration of the prewar German eastern territories. The next two CDU chancellors and their foreign ministers pursued a somewhat more flexible Ostpolitik. The Erhard–Schroeder and later the Kiesinger–Brandt Ostpolitik eschewed the “Moscow-first” basis of Adenauer's Ostpolitik and sought to develop bilateral ties with Eastern Europe without granting diplomatic recognition. This German version of bridge building was based on two assumptions. The first was that the West German economy was bound in the long run to acquire a power and momentum that the countries of Eastern Europe would not be able to withstand. The second was that the FRG's negotiating position and its ability to exert influence were likely to increase with the spread of polycentrism in Eastern Europe.