When U.S. leaders unveiled the Marshall Plan in June 1947, they made it clear that the program would be open to all European nations, not just those in Western Europe. At the same time, they predicated participation in the plan regarding full cooperation and full disclosure, which they knew the Eastern bloc was unlikely to do. Initially, Czechoslovakia, Hungary, and Poland as well as the Soviet Union had exhibited interest in participating in the Marshall Plan. After Molotov left the 1947 Paris Conference, however, the Soviets balked at the plan's guidelines and feared that participation in it would open Eastern Europe to Western influence. Thus, they withdrew from the negotiations and forbade their satellites from signing on to the program.
Molotov subsequently alleged that the Marshall Plan was a disguise for U.S. dominion over Europe and the reintegration of Germany into the capitalist camp. Because of the attractiveness of the Marshall Plan and the dire economic situation in Central and Eastern Europe, an alternative proposal from the Soviet Union became a political necessity. In early 1948 East European states, including Bulgaria and Romania, concluded bilateral treaties of friendship, cooperation, and mutual assistance with the Soviet Union. In January 1949 they became member states of Comecon, which was established to carry out the economic, ideological, and political integration of Soviet bloc nations.
Molotov, Vyacheslav. Problems of Foreign Policy. Moscow: Foreign Languages Publishing House, 1949.; Roberts, Geoffrey. "Moscow and the Marshall Plan: Politics, Ideology and the Onset of the Cold War, 1947." Europe-Asia Studies 46(8) (1994): 1371–1386.