Growth of the UN

Since World War II, the UN has grown from 51 original member states to 193 members today. This growth has been largely due to decolonization. After World War II, nationalist movements in Africa and Asia led to the creation of many new countries. One by one, they have been admitted into the United Nations. In 2011, the nation of South Sudan succeeded in seceding (withdrawing) from Sudan, thus becoming the newest country in the world.

Would you like to join the United Nations? It might help to picture an initiation ceremony for a very prestigious club. Before you can become a member, you must first make a very solemn promise:  

• I promise to abide by all the rules of the UN.
• I promise to respect the principle of non-aggression. (I promise that I will never use force against another state, except in cases of self-defense, or unless I am authorized to do so by the Security Council).
• I promise that I will respect the principle of sovereignty. (I promise that I will never interfere in the domestic affairs of another member state.
• I promise to respect the principle self-determination for all nations. (I promise not to colonize any other country. If my country already owns colonies, I promise that I will give the colonized people a choice: they can either become full citizens of my country, or they can declare independence and become a fully independent sovereign state).
• I promise to respect the principle of human rights. (I promise to respect the idea that all humans are basically equal and deserve to be treated fairly).

After making this pledge, you sign the Charter and you are welcomed as a new member. All those things you promised are now “international laws” that you—and every other member—are legally obliged to keep.