Argentine President Javier Milei has issued a two-week ultimatum to the United Kingdom, threatening to launch international legal proceedings unless Britain halts a major oil exploration project in waters near the Falkland Islands — the South Atlantic archipelago claimed by Argentina as Las Malvinas. In a post on social media platform X, Milei said he had instructed Argentina's Foreign Ministry and legal teams to initiate arbitration against the UK over what he called "the illegal plundering of our resources through the Sea Lion Project," a joint venture between Israeli firm Navitas and British company Rockhopper located approximately 220 kilometres from the islands. If the deadline is not met, he warned, Argentina would bring the case before the International Tribunal for the Law of the Sea, an independent judicial body based in Hamburg that oversees the application of the United Nations Convention on the Law of the Sea. The companies involved have dismissed the threats, stating they hold valid exploration licences issued by Britain.

The dispute centres on a long-running sovereignty conflict that turned into open warfare in 1982, when Argentine forces invaded the islands and a British military task force retook them after 74 days of fighting, leaving 649 Argentine personnel, 255 British troops, and three island residents dead. The islands have since been administered by Britain as an overseas territory. In a 2013 referendum held on the archipelago, 99.8% of voters — on a 92% turnout — chose to remain a British overseas territory. London has repeatedly stated that the question of sovereignty is settled and that the islanders' wishes are paramount, while Buenos Aires maintains the dispute remains unresolved and notes that the archipelago is still listed by the United Nations as a non-self-governing territory.

The latest escalation follows a combative week at the UN General Assembly in New York, where Milei called the organisation "a useless organisation" for failing to act on what he framed as unilateral British actions. Argentine Foreign Minister Pablo Quirno separately exercised the right of reply at the General Assembly, citing what he described as a British occupation dating to 1833. British Prime Minister Andy Burnham, speaking from the same podium a day earlier, had included the archipelago among challenges to the international rule of law, and Britain entered a written rejection of Argentina's position into the assembly's record. Argentina's government already has 60 administrative proceedings open and three criminal complaints against companies and directors involved in hydrocarbon exploration near the islands, though no penalties have been applied and none of the allegations has been proven.

Britain's response has been pointed. Defence Secretary Wes Streeting said in an interview that Argentina "lacks the ability" to retake the Falklands by force and that the UK "has the ability to defend" them, dismissing Argentine claims as "the same old bogus propaganda." The British government has also stated it stands behind businesses operating near the islands, asserting their right to develop natural resources. Meanwhile, some commentary in Britain has linked Argentina's renewed assertiveness to the UK's separate decision to transfer sovereignty of the Chagos Islands in the Indian Ocean to Mauritius, arguing that move signalled weakness that emboldened other territorial claims — a characterisation Milei himself rejected, saying the Falklands strategy had been in preparation for three years. Adding to the diplomatic backdrop, Buenos Aires has grown more vocal on the sovereignty question since US President Donald Trump indicated Washington was open to reviewing its historically neutral position on the dispute.