Here's an idea. Walk out on the U.N. Start a new organization, an invitation only group founded by the US. Make a constitution for the group in which the United States has the power to pick all the members, but is no more powerful than the other nations otherwise. Countries can apply to join, and if we think they ahve some serious human rights violations, they won't get in. If they are led by tyrants, they won't get in. If they are a hate-filled country where terrorists grow on trees, they won't get in. But if their people can live free, and they share the basic ideal that all people are created equal, and should be free to live their lives, then they can get in. Then we'll have an international organization for peace in which the members actually care about peace.

By the way, something like this would not be without precedent. Back in the day, Woodrow Wilson started the League of Nations. It was pretty much useless, as WWII proves, and was disbanded to provide a chance for the UN to get started. Now the UN is proving to be useless. Start again.