The Union of South American Nations (USAN; Spanish: Unión de Naciones Suramericanas, UNASUR; Portuguese: União de Nações Sul-Americanas, UNASUL; Dutch: Unie van Zuid-Amerikaanse Naties, UZAN; and sometimes referred to as the South American Union) is an intergovernmentalregional organization comprising twelve South American countries.
The UNASUR Constitutive Treaty was signed on 23 May 2008, at the Third Summit of Heads of State, held in Brasília, Brazil. According to the Constitutive Treaty, the Union's headquarters will be located in Quito, Ecuador. On 1 December 2010, Uruguay became the ninth state to ratify the UNASUR treaty, thus giving the union full legality. As the Constitutive Treaty entered into force on 11 March 2011, UNASUR became a legal entity during a meeting of Foreign Ministers in Mitad del Mundo, Ecuador, where they had laid the foundation stone for the Secretariat Headquarters. The South American Parliament will be located in Cochabamba, Bolivia, while the headquarters of its bank, the Bank of the South are located in Caracas, Venezuela.
On 4 May 2010, at a heads of state summit held in Campana, 75 km (47 mi) north of Buenos Aires, former Argentine President Néstor Kirchner was unanimously elected the first Secretary General of UNASUR for a two-year term. The new post was conceived as a first step towards the creation of a permanent bureaucratic body for a supranational union, which will eventually replace the political bodies of Mercosur and CAN. The headquarters of the secretariat is located in Quito.
After Argentina, Bolivia, Chile, Ecuador, Guyana, Peru, Suriname and Venezuela, Uruguay became the ninth nation to ratify the constitutive treaty of the organization on 1 December 2010, thus completing the minimum number of ratifications Necessary for the entry into force of the Treaty, on 11 March 2011 With the entry into force of the Treaty, Unasur became a legal entity during the Summit Ministers of Foreign Affairs, in Mitad del Mundo, Ecuador, where the cornerstone was laid for the headquarters of the General Secretariat of the Union.
In April 2018, six countries suspended membership: Argentina, Brazil, Chile, Colombia, Paraguay and Peru.
In August 2018, Colombia announced its withdrawal from the organization.
At the Third South American Summit on 8 December 2004, presidents or representatives from 12 South American nations signed the Cusco Declaration, a two-page statement of intent announcing the foundation of the South American Community. Panama and Mexico attended the signing ceremony as observers in Brazil.
The mechanics of the new entity came out of the First South American Community of Nations Heads of State Summit, which was held in Brasília on 29–30 September 2005. An important operating condition of UNASUR is that no new institutions will be created in the first phase, so as not to increase bureaucracy, and the community will use the existing institutions belonging to the previous trade blocs.