What is NATO's purpose in the 21st century?

In the post-Cold War world, NATO no longer serves the role that it did at the time of its creation.  I believe that in the 21^st century, NATO’s purpose is best understood as an organization of countries focused on promoting peace and security even in countries outside of its membership.  Initially created to stop the spread of militarism in Europe and to protect the region from the Soviet Union, the same issues do not necessarily apply as prominently in the contemporary world. 

NATO clearly does not aspire to be an integrated union like the European Union, as it is not comprised of countries specifically in one geographic region, and its focus is mainly on security, whereas the European Union aspires to bind the countries with a mutual currency, travel ease for members of its states, and arguably a collective culture in many ways.  It has more member states than the European Union, but its limited focus on issues of security and its expansion beyond the geographical European region sets it apart.  It seems more like a collective security organization for countries seen as Western, as many Eastern European have only recently been involved, but the United States and Canada are member states. 

In recent years, NATO has intervened in the form of a peacekeeping organization in conflicts such as those in Bosnia and Kosovo, although neither state is a member.  It has used its resources with security for counterterrorism efforts, many of which lie outside of the West.  At the turn of the century, NATO began to integrate countries outside of the traditional Western world, such as countries in Eastern Europe, former Yugoslavia countries, with the notable exception of Turkey becoming a member in 1952.  It has served as an alliance against large foreign powers such as Russia and China, but almost exclusively in the area of security. 

Only time will tell if NATO will progress to defining collective ideals and spreading them to countries around the globe, or if it will step back from promoting ideology and focus entirely on preventing and ending conflicts.  Perhaps it will continue to expand to countries even farther from the original European geographic region, or it might end this period of expansion and focus its attention on protecting and supporting its member countries in future inter-state conflicts.  Regardless of where NATO is going in the 21^st century, it is clear that its purpose is no longer what it was at the time of its establishment.