The two most important communist organizations to which the country belongs are the Warsaw Pact and COMECON. The Warsaw Pact was established in 1955 as a twenty-year mutual defense pact between the Soviet Union, Albania, Bulgaria, Czechoslovakia, East Germany, Hungary, Poland, and Romania. (Albania ceased its participation in the organization in 1961 and officially withdrew in 1968 as a symbol of protest against the invasion of Czechoslovakia). As an instrument of Soviet foreign policy, the Warsaw Pact has served to maintain Soviet hegemony in Eastern Europe and to provide the legal basis for the presence of Soviet troops on the territory of some of the participating states. Romania has consistently refused to acquiesce in Soviet proposals for greater integration of the military forces of the Warsaw Pact states and did not participate in the invasion of Czechoslovakia. After the Czechoslovak invasion the Ceausescu government established a defense council and proclaimed that foreign troops were not to enter Romania for any purpose without prior approval of the Grand National Assembly. During the 1968-71 period the Romanians limited their participation in pact activities as much as possible. Rather than Romanian troops taking part in joint maneuvers of pact forces, participation has generally been limited to a small group of staff officers who attend the exercises as observers. Official Romanian views on the integration of Eastern European communist forces under the pact were forcefully reiterated in early 1970 after the Soviet chief of staff spoke of "combined" or "unified" pact forces. Ceausescu responded by declaring that Romania's armed forces are not subordinated to any authority other than "the Romanian party, government, and Supreme National Command." Although he pledged continued cooperation with the pact and a fulfillment of his country's responsibilities, he asserted that no part of the party's and government's right to command and lead the armed forces would be ceded to any other body. In addition, Ceausescu gave emphasis to the defensive nature of the Warsaw Pact and reiterated the Romania position on noninterference in the internal affairs of another country. Romanian policy toward COMECON has been cooperative in regard to mutually advantageous trade relations with the other member states but has consistently opposed pressures for the integration of their economies. The Soviet Union and the more industrialized of the Eastern European communist states have pressed for economic integration that would include a division of labor among COMECON members and a specialization of production. Romanian leaders, preferring to develop a diversified national economy, have refused the role of supplier of agricultural goods and raw materials that COMECON would have assigned to their country.