In January 1989, the countries discussed in this book were all ruled by communist parties. There was considerable variation in the systems operating in these countries, with extensive private agriculture permitted in Poland and Yugoslavia, for example, and collectivized agriculture elsewhere in the socialist bloc. But there were some common features, too, among them the principle that the communist party should rule, censorship of the press, party and state supervision of religious organizations, and close supervision of any ad hoc associations which, typically, were required to register with the police. The Baltic republics – Estonia, Latvia, and Lithuania – as well as Moldova had been annexed by the Soviet Union during the Second World War; the German Democratic Republic (GDR), Poland, Czechoslovakia, Hungary, Romania, and Bulgaria were, as of 1989, all members of the Warsaw Treaty Organization (WTO), a Soviet-led military alliance known colloquially as the Warsaw Pact. Those same countries were also members of an economic organization known as the Council for Mutual Economic Assistance (or COMECON). Albania was active in both the Warsaw Pact and COMECON until 1961, when relations between that country and the Soviet Union cooled. Yugoslavia broke with the Soviet Union in 1948 and maintained an independent course thereafter. In 1955, the country became one of the founding members of the Nonaligned Movement.