The makeup of the Security Council gives too much power to the permanent members.
The Security Council has no authority to intervene when military dictatorships remove elected governments. There is no authority to protect governments from rebels. The majority of wars today are internal within countries, and the Security Council has no authority to stop these wars.
The United Nations has no military of its own. It must depend on national armed forces to supply troops.
How could the United Nations be restructured to overcome these problems?