Transatlantic relations which has shadowed over US-Europe interactions for more that a half century has experienced a new debate over  the adoption of unilateral policies by the United Stated after September 11. In current evolving international structure, Europe favors a multi-polar and multi-optional system in which the power is multiplied and the balanced role of influential states in international system is promoted while the role of the United States as a liberal hegemon is enhanced. At the present situation the United States is willing for a uni-polar system based on unilateralism and hegemonic order with imperial characteristics.
The present article aims to give an assessment from Europe-US relations and interactions and challenges between the two sides of Atlantic after September 11.