​Who owns the Falkland Islands?
Explainer
jon.wallace
1 May 2026

A US Department of War memo reignited debate over ownership – which is complicated by Argentine independence, British administration, and the principle of self-determination.

The administration of President Donald Trump brought the issue of sovereignty over the Falkland Islands (known as ‘Islas Malvinas’ in Argentina) back into the news in April. A leaked memorandum from the US Department of War mooted a re-evaluation of the British title to the islands – apparently to punish the UK for its lukewarm stance on the US and Israeli war against Iran.Shortly after the memo became public, the UK responded by saying sovereignty over the islands ‘rests with the UK’. But Argentina’s President Javier Milei posted on X that the islands ‘were, are and will always be Argentine’. US Secretary of State Marco Rubio later appeared to dismiss the significance of the War Department memo, saying the US position on sovereignty of the islands remained unchanged. 

Related work

King Charles in Washington: Did the royal visit save the ‘special relationship’? Independent Thinking podcast

The UK’s sovereignty claim to the islands reaches back nearly half a millennium, backed by a reference to the population’s right to self-determination. Argentina has its own claim, based on the distant history of the early encounter of the islands by imperial Spain. This asserts that Argentina’s colonial territorial inheritance from Spain was forcibly disrupted by Britain in the first half of the 19th century.Untangling the claims is complex. According to the doctrine of intertemporal law, it is necessary to review the entire strand of the history of a territorial claim and evaluate each step according to the rules of international law that prevailed at the relevant time.The claims of the UK, France and SpainThe islands were originally uninhabited and unclaimed, which means that any state could legally take possession of them after their discovery. However, Spain claimed that the Pope awarded the islands to Madrid when he issued a bull (or papal decree) Inter Caetera in 1493, a year after Christopher Columbus first landed in the Americas. That bull assigned all lands 100 leagues west and south of the Azores to Spain, excluding rival claims by Portugal, which instead focused on exploring the African coastline. This was ratified by both states in the Treaty of Tordesillas of 1494. But other states did not feel bound by the papal edict, or the treaty to which they were not a party, and proceeded with their own explorations. The first sighting of the islands by a European is often attributed to Englishman Jon Davis in 1590. But the initial firm record of their discovery was created by Dutch Captain Sebald de Weerdt a decade later. In 1690, English captain John Strong made the first attested landing. Since then, Britain claims an uninterrupted title to the islands. But planting a flag on a beach does not fully confer full title. This act has to be followed by what international lawyers call ‘peaceful and uninterrupted display of state authority’ – that is, a sign of the actual administration of the territory.It was in fact the French who, in 1764, established a settlement on the eastern island. King Louis XV of France claimed title shortly afterwards. The British were initially unaware of the French settlement and established their own at Port Egmont on Saunders Island a year later. Meanwhile Spain, still claiming its notional papal title, persuaded the French to withdraw, paying some 600,000 livres in compensation. In 1770, the Spanish removed the British colony at Port Egmont. However, to avert war over the issue, a treaty was concluded reinstating the colony, without prejudice to the legal claims of both sides. By 1774, London withdrew its physical administration from the islands. However, to counter an argument that this implied abandonment of the British claim, a plaque was left in place, proclaiming continued sovereignty. Argentina’s independenceSpain also withdrew from the islands in the wake of the Latin American independence campaigns that started in 1810. It too left a plaque behind, seeking to maintain its claim. However, Madrid never regained control. The United Provinces of the Rio de la Plata, later Argentina, proclaimed independence in 1816. The country was recognized by the UK in 1825, without prejudice to the Falkland Islands. When the United Provinces sought to establish themselves on the islands, the UK protested in view of its own legal claim.

Argentina…asserts that it was forcibly dispossessed of its territory when its administration and settler community were expelled by force of arms by the British.

A period of lawlessness prevailed on the islands after independence. Argentina sent a governor in 1829, triggering a protest from London. After an incident involving US vessels, the USS Lexington was dispatched to clear the islands of whatever Argentinian authority was left by 1831. In 1833, the UK resumed administration. Argentina argues that its title to the islands was firmly established by then. According to the practice pioneered in the Americas during the independence conflicts with Spain, a newly established state would inherit the boundaries of the former colonial power at the time of independence. This, Argentina asserts, would have included the Falkland Islands (or ‘Islas Malvinas’).Argentina therefore asserts that it was forcibly dispossessed of its territory when its administration and settler community were expelled by force of arms by the British.Britain returnsThe UK can answer that Argentina could not have inherited from Spain what Spain did not have, given London’s title to the islands. The UK opposed the rival Spanish claim from its inception. And in any event, Argentina never managed to establish an effective administration on the islands for any length of time. The UK, in contrast, exhibited the ‘uninterrupted and peaceful display of state authority’ on the islands for close to two centuries, at least since 1833. Argentina claims to have consistently protested what it considered British forcible occupation of the islands. That could legally preclude a perfecting of the UK title over time, if it had not had a pre-existing title already. However, Argentina failed to protest for a period of several decades, until it sought to revive its claim by 1885. Even if the UK claim had still been doubtful at that point, this prolonged period of unopposed possession would have been sufficient to consolidate the British title.The self-determination conundrumSelf-determination is a people’s right. It has matured into a firm and foundational right in international law since the wave of twentieth century decolonization. The modern law of self-determination is unique in that it operates retroactively – intended to overcome the historic injustice of colonialism: it therefore displaces any titles based on colonial conquest and possession. According to the doctrine of uti possidetis, colonial peoples exercise that right within the boundaries established by the colonial powers. But Argentina’s claim to the islands on the basis of uti possidetis meets significant obstacles. The doctrine emerged from Latin American practice as a matter of convenience, rather than a rule of law. It only gained binding legal status in the region over time, and for the rest of the world since the 1960s. Even if uti possidetis could be applied to the case of the United Provinces, it would not operate against the UK, which did not participate in the emerging inter-American practice and was not the colonial power from which the United Provinces gained independence. Some scholars argue that Argentina is as a whole the self-determination entity and that its people have therefore been denied full self-determination since independence, because UK occupation of the Falklands prevented Argentinians from taking full possession of territories assigned to them under the doctrine of uti possidetis. These scholars argue that, as self-determination displaces competing titles, the UK must now surrender the islands in order to overturn that historical injustice.But this argument is not persuasive. For one thing, Spain’s title to the territory at the moment of United Provinces/Argentinian independence is doubtful: as noted, the Provinces could not inherit what Spain did not possess. 

Related work

UK ratification of the Chagos Archipelago treaty will not violate international law

Importantly, Argentina itself has not made this argument – even though a superficially  similar one has been made successfully by Mauritius with regard to the Chagos Islands. There, the International Court of Justice (ICJ) held that the UK excised the Chagos Islands from its colonial territory of Mauritius just before it granted independence to it, leaving the promise of full and complete colonial self-determination within the colonially established boundaries unfulfilled. The difference is that Britain already held title to the islands at the point of Argentina’s independence. London therefore did not remove part of the colonial territory just before the grant of independence to the rest of the colony. And Argentina was a colony of, and seceded from, Spain, not Britain. Perhaps unwisely, Argentina claims that it was a fully-fledged state by 1816 and had already at that point inherited the Falkland Islands from Spain, completing its territorial unity. It asserts that the UK forcibly detached that territory from an independent Argentina through an act of war. Argentina therefore accepts that it had completed self-determination and decolonization from Spain within the uti possidetis boundaries at the time of its independence. It may have taken some years to establish its authority over the islands, but in essence, self-determination had been fully delivered at the point of independence from Spain.In this scenario, the right to self-determination for Argentina had been exhausted by the time the UK re-established control over the Falkland Islands in 1833, and the right therefore cannot be applied against London. The supposed use of forceWithout self-determination, Argentina can only legally claim the islands by virtue of the prohibition of the use of force.However, acquiring territory by force only became unlawful since the adoption of the UN Charter in 1945. It has proven unwise, indeed impossible, to try and undo any forcible changes of territory around the globe that occurred before that date. The only exception is the rule of colonial self-determination.

Argentina is presenting the UK possession as an imperialist issue somewhat outside of the law of self-determination. This is an emotional appeal…rather than a legal argument.

In any event, the UK can assert that it did not capture the territory of another state. It merely re-established authority over a territory to which it held good title. Moreover, Britain did not in fact use force. It was the USS Lexington that cleared out the attempted Argentinian administration in 1831, not UK forces. When British authorities returned to the islands to resume administration two years later, there was no resistance and no shots were fired. There was also no mass expulsion of Argentinian settlers, as has been claimed. Most remained and have lived under the UK administration that has now been in place for close to 200 years – with the brief exception of the Argentinian armed occupation of 1982.A people’s right?In the UN General Assembly, Argentina has not asserted that the people of Argentina as a whole will not have completed their colonial right to self-determination until the UK hands over the islands. Indeed, it is avoiding the application of the principle of self-determination, in case it is applied to the actual population of the islands, instead of Argentina as a whole.Argentina is presenting the UK possession as an imperialist issue somewhat outside of the law of self-determination. However, this is an emotional appeal that resonates well with the majority of members of the UN, rather than a legal argument.There was no indigenous or original population that was colonized by Britain when it originally occupied the islands. And Argentina’s own claim is ultimately based on the supposed acquisition of the islands by Spain in the same manner and at the same time.The UN considers the Falkland Islands a non-self-governing territory – a label ordinarily reserved for colonial territories still entitled to self-determination. Argentina strongly maintains, however, that this is a sovereignty dispute, and not a matter of self-determination. The UK, on the other hand, firmly embraces self-determination in relation to the population of the islands. Changing the status of the islands against their will would fundamentally violate this right. The UK has granted the islands full self-government, including the right to determine their future status in the exercise of their right to self-determination, in a constitution enacted in 2008. Over 99 per cent of the population participating in a referendum of 2013 expressed themselves in favour of remaining a British Overseas Territory. Argentina answers this point by claiming that the people on the islands are an artificially implanted settler population whose existence cannot trump Argentina’s territorial claim. However, the UK can point to the fact that well over half of the population has roots on the islands for well over 100 years. Moreover, on closer reading, it is the UK that has the better territorial claim.In something of a compromise formula, the UN General Assembly is consistently pressing for a settlement of the issue through negotiations between both states. While it notes the underlying sovereignty dispute, seemingly siding with Argentina, it also consistently requires that the interests of the population of the islands must be taken into account.  Read More