Union of South American Nations

The Union of South American Nations (USAN), sometimes also referred to as the South American Union, abbreviated in Spanish as UNASUR and in Portuguese as UNASUL, is an intergovernmental regional organization set up by Hugo Chavez to counteract the influence of the United States in the region. It once comprised twelve South American countries; as of 2019, most have withdrawn.

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.

In April 2018, six countries—Argentina, Brazil, Chile, Colombia, Paraguay and Peru—suspended their membership, and in August of the same year, Colombia announced its withdrawal from the organization. In March 2019, Brazil's president Jair Bolsonaro announced his country's intention to withdraw from the organization. On 13 March 2019, Ecuador announced that it would withdraw from the organization. The president of the country, Lenin Moreno, also asked the bloc to return the headquarters building of the organization, based in Quito. On 10 March 2020, Uruguay officially announced its withdrawal from the organization. Brazil rejoined on 5 May 2023.

In January 2019, amid growing concern about Venezuela's Nicolás Maduro, a new group, PROSUL/PROSUR, was advanced to counteract the influence of what countries in the region call a dictatorship in Venezuela. A Chilean summit to organize PROSUL was held on 22 March 2019, and excluded Venezuela. Argentina, Brazil, Bolivia, Colombia, Chile, Ecuador, Uruguay, Paraguay, Peru, Guyana and Suriname were invited to join the new regional bloc.