On 28 September 2026, Argentina’s President announced that he had instructed its Foreign Ministry and the government’s legal teams to institute arbitral proceedings against the United Kingdom under Annex VII of the United Nations Convention on the Law of the Sea, 1982 (UNCLOS). Argentina seeks to prevent the exploitation of hydrocarbon resources in the ‘North Malvinas Basin’ through the project known as Sea Lion. Giving the UK two weeks to adopt necessary measures to halt Sea Lion, Argentina added that it would seek provisional measures from the International Tribunal for the Law of the Sea (ITLOS) to preserve its sovereign rights over its continental shelf.
This post offers a preliminary assessment of the procedural hurdles to Argentina’s anticipated claims before the tribunal, in light of this announcement. We begin by briefly providing a background to the dispute. Afterwards, we address the possible challenges to Argentina’s anticipated claims and provisional measures request, considering the limits of subject-matter jurisdiction under UNCLOS. We then ask what else could be done.
Background to the dispute
There exists a sovereignty dispute between Argentina and the UK over the Falkland Islands/Islas Malvinas in the South Atlantic ocean, east of the Argentine mainland (hereafter, the Islands). Both States have long claimed sovereignty based on different titles of territorial acquisition. The UK relies on its administration of the Islands since 1833 and the Islander’s right to self-determination. Argentina relies on succession of title from Spain and maintains that it has consistently protested the British presence and never acquiesced in it. As Waibel writes, ‘the international community has regarded sovereignty over the Islands largely as a bilateral issue between the UK and Argentina … the UNGA recognized the existence of a territorial dispute, but declined to subscribe to the British view on self-determination.’ United Nations General Assembly Resolutions 2065 (XX) (1965) and 31/49 (1976) note the existence of a sovereignty dispute, inviting the parties to negotiate and refrain from unilateral modifications to the situation. Argentina’s announcement of 28 September 2026 invokes these resolutions.
In April 1982, Argentina tried to take control of the Islands by force, describing its action as ‘the recovery of its national sovereignty’ (UNSC record). After 10 weeks of armed conflict, the UK restored its administration in June of that year. Both sides sustained heavy casualties. In 1994, Argentina’s Constitution was amended to affirm its sovereignty over the Islands and to declare their recovery a permanent objective, to be pursued with respect for the Islanders’ way of life and in accordance with international law. The UK treats the Islands as one of its Overseas Territories, with internal self-government by the ‘Falkland Islands Government’.
In 1995, Argentina and the UK agreed, in a Joint Declaration, to cooperate on hydrocarbon exploration and exploitation in a Special Area off the Islands, under a ‘formula on sovereignty’ and without prejudice to either side’s legal position. The arrangement was terminated by Argentina in 2007, citing ‘British unilateral acts uninterruptedly performed since 1995 in spite of Argentina’s repeated protests’.
Today, the Sea Lion project, which prompted Argentina’s recent announcement, is being developed under petroleum licences granted by the Falkland Islands Government, with the UK’s ‘full support’.
Given the sovereignty dispute over the Islands, there is also a dispute concerning sovereign rights over the surrounding maritime areas. State sovereignty over the coastal land is the starting point for any entitlement to maritime areas and the exclusive control of natural resources in the maritime areas in question. Like most territorial-maritime disputes, the Argentina-UK dispute ebbs and flows, with some periods uneventful for the most part, and others of escalating tensions, usually in the form of claims and rejections of said claims. What we see now is yet another period of elevated rhetoric.
However, as far as we are aware, this is the first time that Argentina has publicly expressed an intention to file proceedings under UNCLOS in this respect. Both States are parties to UNCLOS, but have chosen different procedures under Article 287: Argentina chose ITLOS, and the UK the International Court of Justice. Thus, by default, the case will come before an arbitral tribunal under Annex VII of UNCLOS, unless the parties decide otherwise.
Pending the constitution of this tribunal, Argentina may request ITLOS to prescribe provisional measures under Article 290(5) of UNCLOS. One of the conditions for prescribing provisional measures is that the future tribunal would prima facie have jurisdiction; a requirement that Argentina will have to navigate carefully.
Jurisdiction under UNCLOS
The compulsory dispute settlement system of UNCLOS may only be invoked with respect to disputes ‘concerning the interpretation or application of this Convention’ as per Article 288(1). Issues of territorial sovereignty, however, are not regulated by UNCLOS.
In the 320 articles and nine annexes of UNCLOS, not a single provision addresses the question of which State may hold sovereign title over a given land territory. The only explicit reference to such disputes is in Article 298(1)(a)(i), which simply allows States to exclude from compulsory conciliation those disputes that necessarily involve the concurrent consideration of sovereignty disputes. Indeed, many UNCLOS provisions proceed on the assumption that sovereignty issues have already been resolved. UNCLOS repeatedly refers to the ‘coastal State’ as the entity from which maritime jurisdiction flows, without defining what constitutes a coastal State. As Beckman notes, ‘territorial sovereignty disputes are governed by rules of customary international law on the acquisition and loss of territory, not by UNCLOS … UNCLOS was never intended to resolve issues of sovereignty.’
Thus, UNCLOS does not, and cannot, determine whether Argentina or the UK is the ‘coastal State’ in respect of the Islands. In the event Argentina claimed sovereignty over the Islands before the Annex VII tribunal, directly or indirectly (e.g., by asserting sovereign rights over the adjacent continental shelf), the claim would not concern the interpretation or application of UNCLOS and would fall outside the tribunal’s subject-matter jurisdiction. Indeed, in every instance where a claim brought before Annex VII UNCLOS tribunals required them to decide a question of unresolved sovereignty over land territory, UNCLOS tribunals have declined to do so (see BIICL, Mixed Disputes).
In Chagos Marine Protected Area (Mauritius v. the UK, 2015), Mauritius argued that the UK was not the coastal State entitled to declare a marine protected area around the Chagos Archipelago. The majority held that this was, in reality, a dispute about land sovereignty, over which it had no jurisdiction. In 2021, an ITLOS Special Chamber in Mauritius/Maldives ruled that there was no longer a dispute over the Chagos Archipelago between Mauritius and the UK, underscoring the authoritative reasoning of the ICJ’s 2019 advisory opinion, which found that the UK’s possession of the territory was unlawful. Thus, in effect, the UK now had no sovereignty or sovereign rights in respect of the Chagos Archipelago. In Coastal State Rights (Ukraine v. Russia, 2020), the Annex VII tribunal held it had no jurisdiction to the extent Ukraine’s claims required it to decide, directly or implicitly, the sovereignty status of Crimea. Similarly, in South China Sea (The Philippines v. China, 2015), the Annex VII tribunal only upheld its jurisdiction to the extent it could decide the claims without ruling on sovereignty over any of the features in the South China Sea.
Unlike in Mauritius/Maldives, Argentina cannot point to an authoritative finding by the ICJ in its favour, such as to render the sovereignty issue moot. ITLOS Judges will be aware and will certainly be reminded of the unresolved sovereignty dispute potentially underlying the maritime claim. If ITLOS found no prima facie jurisdiction over Argentina’s claims, it would decline to prescribe provisional measures to halt the Sea Lion Project.
Obligation to maintain the status quo?
Argentina is presumably aware of this litigation trend. Therefore, the President’s announcement also invokes UNGA Resolutions 2065 (XX) (1965) and 31/49 (1976), arguing that the UK must not unilaterally modify the situation. This might indicate that Argentina will raise a claim alleging that the UK is under an obligation to maintain the status quo in the areas surrounding the Islands, pending the parties’ resolution of the sovereignty dispute and related sovereign rights at sea.
The obligation to refrain from taking actions that would modify the territorial status quo is very similar to the obligation found in Articles 74(3) and 83(3) of UNCLOS in relation to undelimited maritime areas (BIICL, Undelimited Maritime Areas). Pending maritime delimitation, States must exercise ‘self-restraint’ in undelimited maritime areas and avoid actions that would have the effect of aggravating the dispute; although, as Nishimoto explains, ‘it is not a simple matter to determine what kinds of activities constitute a violation of the obligation of self-restraint.’ In South China Sea, the Annex VII tribunal found that this obligation of ‘restraint’, or of ‘non-aggravation’, flows from the requirement to pursue peaceful settlement under Article 2(3) of the UN Charter and also from the principle of good faith. As Yiallourides has written elsewhere, non-aggravation has gained momentum ‘in the broader context of the peaceful settlement of international disputes, particularly territorial and maritime disputes which are often prone to armed escalation and pose risks to peace and security.’
The invocation of an obligation to maintain the status quo and not to aggravate the dispute, i.e., to refrain from making the dispute worse, or otherwise more difficult to resolve, may, at first, seem less controversial than an assertion of sovereignty. It would mean that ITLOS and the Annex VII tribunal may not be asked to rule, directly or implicitly, on Argentina’s alleged sovereignty and associated continental shelf rights. However, to replace the sovereignty question with a question about the maintenance of the status quo would simply restate the problem. Disputes under Article 288(1) must concern the interpretation or application of UNCLOS. Claims concerning the alleged effects of UNGA resolutions, or obligations under general international law, including Article 2(3) of the UN Charter, may not necessarily be about the interpretation or application of UNCLOS. For example, the Annex VII tribunal in Arctic Sunrise (The Netherlands v. Russia, 2015) and ITLOS in M/V Norstar (Panama v. Italy, 2019) did not accept that claims of human rights violations per se could be instituted under Article 288(1).
Though Articles 74(3) and 83(3) of UNCLOS are linked with non-aggravation, they relate to maritime boundary delimitation, which presupposes overlapping maritime entitlements. In the present situation, however, the dispute appears to be generated solely by a sovereignty dispute over land territory. If the UK, as Argentina argues, is not sovereign over the Islands, then there are no overlapping maritime entitlements, and hence no maritime delimitation dispute to be resolved. Articles 74(3) and 83(3) would accordingly not apply. Thus, non-aggravation, by itself, would not necessarily remedy the jurisdictional gap.
Other possible claims
The question remains whether there may be other UNCLOS provisions that Argentina might seek to invoke. One possibility could be for Argentina to follow Mauritius’ strategy with its alternative claim in Chagos MPA, where it argued that the UK exercised the rights of a coastal State in a manner not consistent with the rights of Mauritius. However, characterising the UK as the coastal State, even in the alternative, might be seen as implying a concession that the UK may have sovereignty over the Islands.
Separately, in Coastal State Rights and South China Sea, one of the categories of claims admitted by the Annex VII tribunals related to the respondents’ obligations concerning the protection and preservation of the marine environment. Marine environmental obligations under UNCLOS could be agnostic as to which State has sovereignty. Likewise, environmental claims and associated provisional measure requests under Article 290 of UNCLOS may be brought independently of the claims relating to the preservation of the parties’ sovereign rights.
Reportedly, an Argentinian federal Judge has ordered the halting of the Sea Lion project on the basis that it threatens marine ecosystems and wildlife. Thus, at least for the purposes of establishing jurisdiction, Argentina might point to the alleged adverse environmental effects of Sea Lion. Whether such a claim is plausible depends on an assessment of the facts. To secure a provisional measure halting the Sea Lion project, however, Argentina will have to provide evidence of ‘something more specific than general considerations of environmental harm’.
What else could be done?
The UK may or may not be sovereign over the Islands; Argentina certainly maintains an active sovereignty claim over the Islands. Any solution must only be reached by peaceful means, requiring a genuine attempt by the parties to engage with a view to resolving the dispute (see BIICL, Territorial Disputes). Marcelo Kohen prepared a proposal in 2018, providing for a negotiated transfer of sovereignty to Argentina, combined with Island autonomy (as reported here). This seems difficult to achieve at present as the UK insists that the matter is closed, allegedly given the territory’s people’s wish to remain a British Overseas Territory.
Another approach, if only to prevent the dispute from exploding again in the future, would be to negotiate a joint special regime, i.e., joint management or joint exercise of sovereignty. The objectives could include, first, ensuring equitable access to the maritime areas adjacent to the Islands, and second, promoting cooperation in areas such as science, environmental protection, and tourism. Crucially, any such cooperative regime could also include demilitarisation, which is always an important element in any peace process. International courts and tribunals, from the North Sea cases (1969) and Eritrea/Yemen (1999) to the Guyana/Suriname (2007) and Ghana/Côte d’Ivoire (2017) cases, have emphasised that parties to a dispute can draw mutual economic benefits by cooperating in a disputed area.
The UK and Argentina were able to agree on a joint cooperative regime in 1995. Perhaps, the option of another special regime reflecting present day realities and environmental conditions should now be reconsidered. Argentina’s Foreign Ministry has already reiterated its readiness to resume bilateral negotiations.
The next stage of this longstanding dispute remains to be seen.