Ideological schism occurs between different communist countries as national systems emerge to cope with varying conditions. Schism may result in the withdrawal of cooperation or participation in international communist activities; or it may develop into cold war, with a high degree of tension on both sides. Political purges, censorship and repression may become more intense, and frontiers may be closed. Outwardly it may encourage imperialism on the part of the orthodox communist power, or two different communist countries to fight for prestige and the ideological leadership of the communist world system; or it may intensify their economic imperialist activities, competition with one another, and their propaganda.