A joint training exercise with a small contingent of United States military personnel in southern Argentina has been drawing criticism by opposition members who say President Javier Millei failed to notify Congress about the exercise.
The controversy comes as tensions between the United Kingdom and Argentina have escalated in recent weeks over control of the disputed Falkland / Malvinas islands off the south-eastern coast of Argentina.
On September 16, Argentina's Navy confirmed the presence of eight U.S. Marines in the southern province of Tierra del Fuego after pictures of the soldiers circulated on social media. Authorities said the soldiers were part of a joint exercise with the 4th Marine Infantry Battalion (BIM 4) in Ushuaia, as part of a "cold weather expert exchange." They said the exercise began September 8 and will end on September 22.
Law 25.880 of Argentina's Constitution establishes a procedure by which the Executive Branch must request authorization from the National Congress as stipulated in Article 75, Section 28 of the National Constitution, to allow the introduction of foreign troops into the territory of the Nation and the deployment of national forces outside of it.
While President Milei has sidestepped this law recently by issuing emergency decrees to allow foreign troops onto Argentine soil — including in September 2025 and April 2026 – he reportedly failed to issue any such decree or notify the legislature for this training exercise.
The military exercises are drawing concerns from local officials in Tierra del Fuego, in southern Argentina, where the training is taking place.
Andrés Dachary, Secretary of the Falkland (Malvinas) Islands, Antarctica, South Atlantic Islands, and International Affairs of Tierra del Fuego, told International Business Times, "It constitutes a flagrant institutional irregularity and a violation of the National Constitution, which places the responsibility of authorizing the entry of foreign troops into national territory on the National Congress."
Likewise, the official declared that the Permanent Bicameral Legislative Procedure Commission is also failing, as "there is an alarming disregard on the part of this body, which delays or directly does not address these decrees, ignoring the absolute lack of accreditation of the 'necessity' and 'urgency' required by Article 99, Section 3 of the Constitution to justify exceptional measures."
Dachary clarified: "By not issuing or subjecting these decrees to immediate rejection in the chambers, the Bicameral Commission is allowing by omission the Executive [branch] to bypass democratic debate, empty the content of the Legislative [branch's] powers, and undermine our territorial sovereignty through the back door,"
Joint tasks between the U.S. and Argentina
This is not the first time that American troops have entered Argentina under the current administration. Previously, the government of Javier Milei authorized two entries by decree: the first in September 2025, for joint exercises in the southern region such as Ushuaia and the deployment of local troops to Chile; and the second in April 2026, to allow the deployment of Special Operations Forces from the U.S. Southern Command and naval assets.
"What stands out in this third visit is the alignment that Milei maintains with his North American counterpart within the framework of bilateral cooperation," Mariana Altieri, a geopolitics specialist and founder of the Meridiano Foundation, told The Latin Times.
Altieri said, "Donald Trump defends his own interests in the South Atlantic and takes advantage of the affinities he has with right-wing leaders in the region to obtain concessions that no other Argentine government aligned with the United States, as was the case with Menemism (1989-1999) or Macrism (2015-2019), would allow to the detriment of sovereignty. In this case, Milei would be willing to do anything Trump asks of him, and that is complex for Argentina's own interests."
La Armada confirmó presencia de soldados de Estados Unidos en Ushuaia , operando sin autorización del Congreso
— La Política Online | Argentina (@LPOArg) September 16, 2026
[https://t.co/7rloRdiuBA] pic.twitter.com/mqn44VkpVY
Beyond questioning the legality of the U.S. troop presence in Tierra del Fuego, their arrival amid the current geopolitical context in the region is also raising eyebrows.
The Falkland Islands are an archipelago located 430 miles east of Tierra del Fuego, in the South Atlantic Ocean. It is a territory disputed by the United Kingdom and Argentina. The latter claims them as part of its national territory due to their geographical proximity and being the first to settle in the area.
However, in 1833, the British forcibly occupied the islands and expelled the Argentines living there. Subsequently, on April 2, 1982, a war broke out between the two countries that lasted 74 days and resulted in the deaths of 649 Argentinians, 255 Britons, and three island civilians. Argentina signed its surrender, and the United Kingdom has administered the territory since then.
In this context, last Thursday, September 4, President Milei announced that Argentina would impose sanctions on all oil companies operating without Argentine permission in the archipelago. Additionally, he announced by decree the expansion of the budget to continue constructing the Military Base in Ushuaia. For its part, Great Britain reacted by ordering the modernization of military capabilities at the Royal Air Force base in Monte Pleasant in the islands, including the replacement of combat aircraft.
Dachary said the deployment of British military aircraft to the Falklands / Malvinas islands "is a direct provocation and a threat to the entire region, as it implies an unjustified escalation in the militarization of the South Atlantic, flagrantly violating the commitments of the South Atlantic Peace and Cooperation Zone (ZOPACAS)." He added that London "seeks to consolidate a military fortress to protect the plundering of our fishing and hydrocarbon resources."
In contrast, Argentina has "historically worked to keep the South Atlantic free from global geopolitical tensions, a commitment internationally enshrined in the ZOPACAS," he said.
For its part, the British Labor government published a document titled "Doing business with the Falkland (Malvinas) Islands" to defend the fishing and oil exploitation that could take place in the disputed area in the coming years. In the guide, it emphasized, "Argentina does not exercise sovereignty or jurisdiction over the Falkland Islands."
For Altieri, the statements align with the UK's longtime position on the matter, as "they insist on not recognizing Argentine sovereignty over the Falklands since 1833, when they were usurped."
The U.S. troop presence also caused discomfort amongst some of Argentina's opposition figures.
On September 17, Peronist Senator Cristina López formally submitted a Question of Privilege against Milei's government to the High Chamber's Entry Desk – a legal tool through which a legislator denounces in the chamber that the guaranties or institutional sovereignty of the Chamber have been violated.
Senator López said, "Another concern deepens: on October 20 and November 15 [2025], with the authorization of the National Government, U.S. military troops arrived to conduct joint exercises in the city of Ushuaia. The same situation is happening now with the presence of U.S. Marines, violating our Constitution, without authorization from Congress, as established by Article 75, section 28."
Argentine Defense Minister Carlos Presti sought to ease tensions with the United Kingdom by telling the press that "the claim is being pursued through diplomatic and peaceful channels." Furthermore, he stated that "no one is losing sleep" over the possibility of a military escalation in the dispute over the archipelago and asserted that the alliance with the United States "positions us to achieve territorial integrity."
The dispute over the Falkland Islands, a strategic enclave of the South Atlantic
The Falklands/ Malvinas is an archipelago of over 700 islands encompassing around 4,700 square miles in the southern Atlantic Ocean. They are referred to as a gateway to the Antarctic and are rich in hydrocarbons and fishing.
Moreover, it is an area whose geographical position provides access to the control of the Drake Passage and Cape Horn, the only natural navigation routes between the Atlantic and Pacific Oceans.
Due to its great strategic value, the Integrated Naval Base project in Ushuaia, Tierra del Fuego, is reaching a decisive milestone. The project, whose construction began in March 2022 under the administration of Alberto Fernández as a strategic infrastructure for national financing and sovereignty, has been reoriented by Milei's administration.
Now, the government has decided to allocate greater budgetary funding to accelerate the development of the site, but redefining its function. The base has transitioned from being a self-sufficient project to becoming a key logistical center for strategic cooperation in the South Atlantic.
Altieri pointed out that the military base "is something that has been demanded for a long time."
It won't come cheap either. Dachary added that the project would involve "infrastructure specific to national defense, oriented toward the sovereign functions of the State, such as patrolling, controlling maritime spaces and the bi-oceanic passage, and safeguarding life at sea (search and rescue)."
Additionally, it includes the creation of the "Antarctic Logistics Hub, an initiative with a civil, scientific, and commercial imprint, structured under a public-private management model."
He said that both projects aim at "safeguarding Argentine sovereignty and security in a key maritime passage for global trade, and operating as a driver of economic development and international services of excellence."
In September, Milei's government sent a 2027 budget proposal to Congress that includes a 24.4% increase in the defense budget compared to the previous year, as well as authorization to incur debt of up to USD $3.5 billion to acquire three submarines and two frigates for the Navy.
Presti said these acquisitions aim to "strengthen our defense system" and that they are not "related to other international issues," dissociating the measure from the Falklands / Malvinas dispute.
