In terms of trading practices, countries may be allocated to one of three categories: developed market economies, centrally-planned (or former socialist) economies, and developing countries. Trade between countries of different systems is weaker than that between countries of the same system. The differences in the trading practices between two economic systems has acted and continues to act as an impediment to trade expansion. Consistent trade practices are especially hindered by political intervention into the market, such as the USA grain embargo of 1980. Rapid changes cannot be expected because of such differences.
In 1972, despite considerable expansion in East-West trade over the past decade, 63.5% of the export trade of the eastern European socialist countries was to socialist countries, and 22.4% was to developed market economy countries. In 1982, Western industrialized states counted 4.8% of their trades as being with socialist economies. Socialist economies counted 31.7% of their trade with the Western market economies. While it is relatively weak, trade between former COMECON countries and OECD countries is growing, after the 1982 recession. However, this trade flow is characterized by an unsatisfactory commodity structure, persistent imbalances, limitations and restrictions of different kinds and the level of cooperation is below what is feasible.