First of all, the US created the UN and other international institutions against the will of Europeans and most other nations, who, prior to Willsonian idea of collective security, did not understand or attempt any form of international relations not based on balance of power. Not disagreeing that there are many of us in the US (myself included) who think this is dumb on our part, but it is just a little bit unfair to single out the country that contributed the most to international cooperation as being against it.
Btw, international cooperation today is greatest it has ever been due to capitalism and globalization so you should be happy. Just about every person in the world is involved in voluntary and productive cooperation as well as competition with people all over the world within the global market. Lookup Milton Friedman's example of a pencil: http://www.youtube.com/watch?v=R5Gppi-O3a8 for a beautiful illustration.
Governments are not the place to look for any kind of cooperation that sacrifices the interests of their country for others, even a little bit. It is not only very difficult and unnatural for such a thing to happen in any democracy as such gov. will not last very long, but it is morally suspect as well. Try running for election in any country on a platform of say reducing welfare benefits or increasing taxes for citizens of that country in order to help the starving in other countries in the name of eliminating nationalism and patriotism and see how far that gets you,