Here are the United Nations Charters.

International treaties are meant for nations to get together, to solve differences, to warn a country when it denies and breaks treaties or to join forces against an enemy.
If there are 280 million americans, there are 6 billion inhabitants in the world. Who is right?
Has one country the right to claim changing the purpose of treaties without the other ones' consent and approval?

Our Constitution provides that treaties signed by the President and ratified by the Senate are part of the "supreme Law of the Land." The United Nations Charter, which our nation wrote in large part, and signed and ratified as a treaty in 1945, provides that — except in response to an armed attack — nations may neither threaten nor engage in warfare without the authorization of the UN Security Council. President Bush swore to uphold and defend the Constitution. Yet he advocates a right to ignore our treaty obligations and to visit the scourge of war upon Iraq, with or without the approval of the United Nations.

Treaties took years to be approved, because they involve so many nations around the world.
Any law student knows there are rights and obligations, not just in the individual lelvel, but in the nation level. We also know, through history, what happened to empires, and why.
We understand why our great-grandparents wanted to create the League of nations, why it failed. The UN isn't perfect; it is no government by itself, it has only coordination power and no coercive power. If it needs replacement, this will need consent from all the other countries, or at least a large enough number of them to have any credibility.

Raoul