 Initially, the Comecon served as cover for the Soviet taking of materials and equipment from the rest of the Eastern Bloc, but the balance changed when the Soviets became net subsidizers of the rest of the Bloc by the 1970s via an exchange of low cost raw materials in return for shoddily manufactured finished goods.In 1955, the Warsaw Pact was formed partly in response to NATO's inclusion of West Germany and partly because the Soviets needed an excuse to retain Red Army units in Hungary.For 35 years, the Pact perpetuated the Stalinist concept of Soviet national security based on imperial expansion and control over satellite regimes in Eastern Europe.