I disagree that the UN is an effective mechanism for global governance now. I would assert that the UN has very little to do with global governance because it is essentially an actionless body. It is a way for nations to express their opinions but there is no enforcement mechanism. Countries are not bound to abide by UN resolutions. The UN can pass resolution after resolution but ultimately if it is to get anything done it is by voluntary compliance by its members. If a country doesn't wish to comply then there is nothing the UN can do to make it comply, other than what member states volunteer to do.
That being said, I would say that even though there is no true international government, all the international governing bodies such as the UN, NATO and other such bodies are important places for the US to show leadership. It appears that President Bush has just started his international political campaign to get foreign countries on board to support enforcement of the UN's resolution to destroy weapons of mass destruction in Iraq.
Since September 11, the government and a majority of US citizens have come to the conclusion that we must be proactive in fighting terrorism around the world to prevent future terrorist acts against us. The Bush administration has interpreted this to mean that we should use our leverage to enforce the elimination of WOMD in Iraq. Even our usually flaky regional friends in Egypt, Saudi Arabia and some other Arab states must agree on some level with the goals of Bush's administration because they are allowing the US to use their bases for the next campaign against Iraq even while they publicly urge caution.
