Argentina has handed the United Kingdom a two-week deadline to stop oil production at the Sea Lion field in the North Falkland Basin, warning that it will take the dispute to the International Tribunal for the Law of the Sea (ITLOS) if London does not comply.

The demand came in a statement from the office of Argentine President Javier Milei, published on 29 September. Buenos Aires calls for concrete measures within two weeks to prevent hydrocarbon production near the Falkland Islands, which Argentina refers to as the Malvinas.

The ultimatum lands on a project with material scale. Sea Lion, located roughly 220 kilometres from the Falkland Islands, carries an estimated resource of up to 1.7 billion barrels of oil. UK-based Rockhopper Exploration and Israel's Navitas Petroleum are developing the field, making the partners the immediate commercial targets of the Argentine move.

The legal vehicle Buenos Aires has chosen carries real teeth. ITLOS, seated in Hamburg, operates under the UN Convention on the Law of the Sea and adjudicates disputes between states over maritime boundaries, rights to marine resources and navigation. The tribunal can order legally binding provisional measures — including suspension of specified activities — while a dispute remains under consideration. That provision is the mechanism that could, in theory, reach drilling and production operations pending a final ruling.

For the operators, the two-week clock now frames the near-term risk. Rockhopper and Navitas have not commented publicly on the deadline, and the UK government's response remains outstanding. The dispute sits squarely on the sovereignty question that has shadowed Falklands exploration for decades: Argentina claims the islands and their surrounding waters; Britain administers them and licenses exploration accordingly.

Argentina's move is not an isolated legal strike. Argentine authorities have already initiated legal proceedings against Navitas Petroleum, as well as against Canadian companies JHI Associates and Eco (Atlantic) Oil & Gas, both of which hold positions in the Falklands exploration plays. The pattern shows Buenos Aires working systematically through the partner ranks of every licence holder in the basin, using courts as leverage alongside diplomatic pressure.

The timing sharpens the stakes for Sea Lion, the basin's flagship development. Rockhopper discovered the field in 2010, and the project has spent years cycling through redesigns and partner changes as it sought a route to a final investment decision, with Navitas farming in to carry the development forward. An ITLOS filing — even one unlikely to be resolved quickly — would add a layer of legal uncertainty over financing, insurance and contractor commitments for a project already sensitive to cost and schedule risk.

Whether the tribunal would act is a separate question. ITLOS jurisdiction depends on the parties and the claims brought, and provisional measures require a showing of urgency and risk of irreparable harm to marine environments or rights. Any order suspending production would mark an extraordinary intervention in an operating offshore development.

The watch item: the two-week deadline. If the UK does not respond to Buenos Aires's demand, Argentina says it will file at ITLOS — and the tribunal's decision on whether to hear the case, and whether to order provisional measures against Sea Lion operations, becomes the next milestone for the basin's only sanctioned-track development.