Argentina asks law-of-sea tribunal to order UK to halt Sea Lion oil project, tribunal to set hearing

Argentina has asked the International Tribunal for the Law of the Sea to order the United Kingdom to stop development of the Sea Lion oil project north of the Falkland Islands and to bar new permits for exploitation on the disputed continental shelf. The Hamburg-based tribunal said it will assess whether it has prima facie jurisdiction and whether urgent provisional measures are warranted, and it added that a hearing will be set “at the earliest possible date.”

In the filing, Argentina requested four provisional measures: a halt to Sea Lion development; an order preventing use of exploration information to Argentina's detriment; measures to allow Argentina to protect the marine environment in the area; and a prohibition on actions that might aggravate the dispute. The tribunal’s statement said it must first find prima facie jurisdiction and urgency before it can prescribe any provisional measures. Argentina’s submission follows President Javier Milei’s announcement on Sept. 28 that Argentina had initiated arbitration under Annex VII of the United Nations Convention on the Law of the Sea. The filing, and Argentina’s broader legal approach, aim to block or delay hydrocarbon exploitation on a continental shelf area claimed by both Buenos Aires and London. Sea Lion is operated by Navitas Petroleum, which holds 65%, and Rockhopper Exploration, which holds 35%, and project materials cited in the reporting say Sea Lion expects first oil in 2028. Argentina’s request therefore targets a commercially advanced development that companies expect to bring production online within a defined timeframe. London rejected Argentina’s legal move. The British government said it will engage with the tribunal process but also intends to challenge efforts to use the tribunal to resolve sovereignty issues, and the British Foreign Secretary, Ed Miliband, called Argentina’s initiative an attempt to intimidate companies and individuals carrying out legitimate commercial activities in the Falkland Islands. The United Kingdom’s statements frame provisional measures as binding but reserve the right to contest jurisdiction. The tribunal’s routine for provisional measures requires a prima facie finding of jurisdiction and a showing of urgency; if it accepts those thresholds, it can prescribe measures that the parties must observe while the tribunal considers the underlying dispute. Previous cases under the Convention, cited in reporting about the tribunal’s practice, include instances where courts declined to rule on territorial sovereignty questions, which is a central legal tension in this dispute. Argentina’s filing asks the tribunal to enjoin not only ongoing development work on Sea Lion but also any new authorisations to exploit the continental shelf, and it asks the court to bar steps that might worsen the dispute or undermine Argentina’s ability to protect the marine environment. The United Kingdom’s public position is that it will contest any attempt to turn the tribunal into a forum for settling sovereignty, while still participating in the tribunal process. What happens next is procedural: the tribunal will decide whether it has prima facie jurisdiction and whether the urgency threshold is met; if so, it could order provisional measures before a full hearing. A hearing has been promised “at the earliest possible date,” but the tribunal’s statement and the parties’ public positions indicate a contested legal path ahead as both states press their claims through international law and diplomatic channels.