USHUAIA — U.S. and Argentine Marines have completed combat training in extreme cold and mountain terrain in Ushuaia, in the far south of Tierra del Fuego, an exercise U.S. Marine Corps Forces, South says strengthened mobility, emergency response and small-unit coordination.
The exercise ran from September 8 to 22, with intensive training between September 11 and 19, according to Escenario Mundial. Eight U.S. Marine instructors from the Marine Corps Mountain Warfare Training Center worked with Argentina’s Marine Infantry Battalion No. 4 (BIM 4), part of the Austral Marine Infantry Brigade.
The program covered cold-weather and mountain operations, tactical movement and patrolling, simulated responses to hostile fire, long-distance navigation, and amphibious landings in combat rubber raiding craft. “The training developed mobility, emergency-response skills and small-unit coordination across demanding terrain,” MARFORSOUTH said, according to Escenario Mundial.
The exchange has run since 2017 and lines up with BIM 4’s annual winter training in the mountain valleys of Tierra del Fuego, the outlet reported. It sits within broader Argentina–U.S. Southern Command naval cooperation, including the UNITAS multinational exercise, which Argentina is preparing to host in 2027.
The exercise drew criticism at home in Argentina. Argentine law, including Law 25.880 and Article 75 of the Constitution, requires congressional authorization before foreign troops enter the country. Rio Grande Mayor Martín Pérez publicly asked what legal instrument covered the activity, Realidad SM reported.
The Argentine Navy cited no specific decree, and the national government had not publicly addressed the legal basis at the time, according to that report.
The outlet noted that the Executive used decrees in 2025 and 2026 to authorize other combined exercises when Congress had not acted.
Opposition figures also objected, among them Peronist Senator Cristina López and Andrés Dachary, Tierra del Fuego’s secretary for Malvinas affairs.
The training took place as tensions over the Falkland Islands, known in Argentina as the Malvinas, were rising with the United Kingdom. Officials have said the exchange concerned professional expertise and not the islands, according to Realidad SM.
