Amendments to the United Nations Charter
Because Charter amendments require the consent of all five permanent members of the United Nations Security Council—defined in Article 23 of the Charter as "The Republic of China, France, the Union of Soviet Socialist Republics, the United Kingdom of Great Britain and Northern Ireland, and the United States"—it is impossible for other UN member states to force the permanent five to give up their Security Council 'veto power', by means of a Charter amendment. Many reformers have described this situation as a Catch-22. According to Global Policy Forum, "the P-5 are content with the present arrangements and oppose any changes that might dilute or challenge their power or expand their 'club.' China has already announced it will block permanent membership for Japan, and the United States has suggested that it will only support Council reform that commands an implausibly 'broad consensus'".
United Nations Security Council Resolution 1645
The resolution then set out the composition of the commission, to include seven members of the Security Council, seven members of the United Nations Economic and Social Council, the top five providers to the United Nations budget, the top five providers to United Nations peacekeeping missions, with representation from all regional groups. It also discussed country-specific meetings of the commission, where representatives of the World Bank and International Monetary Fund, among others, could participate. The Peacebuilding Commission was encouraged to co-operate with international organisations as appropriate, and provide advice to the Council in matter with which it is seized.