Regional diplomacy

Mercosur Founded 1991

Created by the Treaty of Asunción of 26 March 1991 by Argentina, Brazil, Paraguay and Uruguay. Venezuela was suspended in December 2016 for failing to meet its accession obligations and in August 2017 under the bloc’s democratic clause. Bolivia completed its accession ratification in July 2024. Brazil held the pro tempore presidency in the second half of 2025, handing it to Paraguay at the Foz do Iguaçu summit of 20 December 2025. The EU–Mercosur agreement was signed in Asunción on 17 January 2026, with Mauro Vieira representing Brazil.

Argentina Mercosur co-founder

Background. Argentina is Brazil’s principal regional partner; the rapprochement of the 1980s produced the Declaration of Iguaçu (1985), the ABACC nuclear-safeguards agency (1991) and Mercosur. Vieira was Ambassador in Buenos Aires from 2004 to 2010.

Developments. Vieira represented Brazil at President Javier Milei’s inauguration in December 2023. In July–August 2026, after remarks by President Milei during a visit to Brazil that the Brazilian government regarded as offensive to President Lula and to a Supreme Court justice, Brazil recalled its ambassador and, according to press reports, reduced its representation to chargé d’affaires level.

Brazil’s documented position. In an interview with Clarín published on 9 August 2026, Vieira said that the relationship was “very important” and that such attacks must stop “immediately” for the bilateral relationship to return to normal (archive translation from the Portuguese report).

Uruguay Mercosur co-founder

Montevideo hosts the Mercosur secretariat and ALADI, where Vieira served as First Secretary from 1982 to 1985. Presidents Lula and Lacalle Pou met in January 2023 to discuss border infrastructure and the bloc’s external agenda.

Paraguay Itaipu partner

The Itaipu Treaty of 26 April 1973 created the binational hydroelectric plant on the Paraná river. The treaty’s financial annex (Annex C) came up for revision in 2023, fifty years after signature. Paraguay took over Mercosur’s pro tempore presidency from Brazil in December 2025 and hosted the EU–Mercosur signing in January 2026.

Bolivia Mercosur member since 2024

Energy links — above all the 3,150 km GASBOL gas pipeline, operating since 1999 — have long anchored the relationship. Bolivia’s Mercosur accession protocol, signed in 2015 and approved by Brazil in 2023, was ratified in July 2024; Bolivia has up to four years to adopt the bloc’s rules.

Chile Free trade partner

The Brazil–Chile Free Trade Agreement, signed on 21 November 2018, entered into force on 25 January 2022. Chile was Brazil’s ninth-largest export market in 2025.

Colombia Amazon partner

Presidents Lula and Petro met in Leticia on 8 July 2023 to prepare the Belém Amazon Summit. Colombia joined Brazil and Mexico in joint statements on the 2024 Venezuelan election. Vieira represented President Lula at the inauguration of Colombia’s new president in Cali on 7 August 2026.

Venezuela A sensitive file

Background. Diplomatic relations were downgraded during the previous Brazilian government; Brazil’s embassy in Caracas, closed in 2020, reopened in 2023. Venezuela remains suspended from Mercosur.

Brazil’s documented position. After the presidential election of 28 July 2024, Brazil, Colombia and Mexico issued joint statements; the second, on 8 August 2024, called for the publication of results broken down by polling station. In August 2024 the President’s special adviser, Celso Amorim, told the Senate that Brazil would not recognise results without the voting records. A Senate committee hearing at which Vieira was to be questioned on Venezuela, scheduled for October 2024, was cancelled.

Developments. On 3 January 2026 a US military operation in Venezuela resulted in the detention of Nicolás Maduro. At a Security Council meeting on 5 January, Brazil said the action had “crossed an unacceptable line”, according to UN News.

International perspectives. Governments across the Americas and Europe took differing positions on both the 2024 election results and the January 2026 operation; readers are referred to the sources for the range of views.

The Amazon ACTO · COP30

The Amazon Cooperation Treaty of 3 July 1978 links the eight Amazon countries. Brazil hosted the Amazon Summit in Belém on 8–9 August 2023, which adopted the Belém Declaration, and returned to Belém to host COP30 in November 2025.

CELAC and UNASUR Returned 2023

Brazil rejoined CELAC in January 2023, after suspending participation in 2020, and returned to UNASUR in April 2023, after withdrawing in 2019.