A two-week deadline now hangs over the Sea Lion development in the North Falkland Basin, days after the project's partners took final investment decision on a field holding an estimated 1.7 billion barrels of oil.

Argentine President Javier Milei issued the ultimatum on social media, demanding the UK halt work at Sea Lion or face international legal action. If operations continue past the deadline, he said, he has "instructed the Foreign Ministry and legal teams to initiate international arbitration" over what he called "the illegal plundering of our resources through the Sea Lion Project."

Argentina also intends to escalate the dispute to the International Tribunal for the Law of the Sea should activity persist after the two-week window.

Sanctioned project, named partners

Sea Lion sits roughly 220 km north of the Falkland Islands within production licences PL032 and PL004b, both issued by British authorities. Tel Aviv-listed Navitas Petroleum operates the field with a 65% working interest; London-listed Rockhopper Exploration holds the remaining 35%. Rockhopper published the 1.7-billion-barrel reserve estimate for the asset.

The legal pressure lands at a pivotal moment for the scheme. Navitas Petroleum Development and Production, Navitas' UK subsidiary, and Rockhopper have taken FID on the Sea Lion Northern Development project, securing approvals and funding for full-scale execution. Development work could begin within the next few months, with first oil targeted by March 2028.

Pressure beyond arbitration

Milei is pressing on several fronts. He criticised the UN for inaction on the long-standing sovereignty dispute, calling it "a useless organisation" serving "arrogant parasites dressed up as well-intentioned bureaucrats."

Earlier this month, he signaled plans to send an urgent sovereignty defence bill to Congress that would tighten penalties against companies operating around the islands without Argentine authorisation. The proposed changes would widen sanctions to cover corporate directors, shareholders and suppliers — a clause structure that could reach contractors and service providers well beyond the two licence holders themselves.

The UK government has pushed back. Defence Secretary Wes Streeting said Argentina "lacks the ability" to reclaim the Falklands by force, the BBC reported.

Contested ground, working rigs

The sovereignty dispute over the islands — Las Malvinas in Argentina — dates to the 1982 conflict, when a British task force retook the territory after an Argentine occupation. A 2013 referendum saw 99.8% of islanders vote to remain a British Overseas Territory.

None of that has stopped the basin from moving. Sea Lion remains the flagship development in frontier acreage that Rockhopper and its partners have held through multiple exploration cycles, and the FID converts years of appraisal work into a funded execution plan.

The watch items: whether Argentina actually files at the International Tribunal for the Law of the Sea once the deadline lapses, how quickly the Milei government's sanctions bill advances through Congress, and whether the March 2028 first-oil target survives the diplomatic and legal friction now attached to the development schedule.