Argentina–Chile relations refers to international relations between the Republic of Chile and the Argentine Republic. Argentina and Chile share the world's third-longest international border, which is 5,300 km (3,300 mi) long and runs from north to the south along the Andes mountains. Although gaining their independence during the South American wars of liberation, during much of the 19th and the 20th century relations between the countries were chilled as a result of disputes over the border in Patagonia, although Chile and Argentina have never engaged in a war. In recent years relations have improved dramatically. Despite increased trade between the two countries, Argentina and Chile have followed quite different economic policies. Chile has signed free trade agreements with countries such as China, the US, Canada, South Korea and the EU and is an active member of the APEC, while Argentina belongs to the Mercosur regional free trade area. In April 2018, both countries suspended membership of the Union of South American Nations.