The distribution of power is a major source of diverging opinions between the United States and Europe. Europe is militarily weak but economically strong, and its foreign policies are shaped by that position. America is economically strong to be sure, but it is also the strongest military power in the world. The foreign policy of the United States reflects its confidence as a military force. Each region seeks a world system that will complement its own position of power in the world, one that will guarantee the greatest degree of security for itself. .
Europe has little military power, and thus stands to benefit from working within international law and establishing diplomatic relations. America, however, is a strong military power that desires as much freedom to implement that power for its own protection as possible. Thus American policymakers reasonably shy away from rules that would limit America's freedom to use force as deemed necessary to protect its interests.
It is not, however, just that Europe has a weak military and cannot build it up; rather, Europeans have a different ideology than Americans. Given Europe's experiences with power and diplomacy in the past decade, it makes the most sense to Europeans that they avoid military force and focus on diplomacy and security organizations. .
Until Europe regains a power that could approximate that of the U.S., the two regions will continue to have divergent approaches to foreign policy. This does not mean that the two will not continue to work together. There has been contention about global policy since the end of the Cold War, and the aftermath of September 11, 2001, dramatic though it was, has not permanently changed the relationship. The fundamental nature of US-European relations still requires that Europe rely on US military power for protection, and that the US rely on Europe to give it a measure of legitimacy and for economic relations.