The relationship between CMEA and EC

In early 1970 responsibility for the conclusion of trade agreements was transferred from the individual member states to the EC. Since then the EC has been recognized throughout the world as a contractual partner in its own right within this area. Only the Soviet Union and the CMEA are being difficult accepting these changes in responsibility since 1970. This means that in trade between the EC countries and the state trade countries there exists at present a situation without treaties. Where do the problems lie? What models offer themselves for overcoming this situation?