Similarities and differences do matter in the scope of international relations. When those aspects of similarities and differences over the transatlantic relations are narrowed down, it is inevitable to come across the changing patterns of foreign policy. Specifically, when the mutual relationship between the United States (hereafter, the US) and the European Union (hereafter, the EU) is taken into account, a question is revealed about how can differences in interests be converged in a manner of joint cooperation in foreign policy areas?