Chagos Islands: Britain is Leaving, But Not Leaving

It happened quietly and loudly at the same time. Quietly, because most people were distracted by domestic noise, budgets, rail strikes, and the endless low-grade hum of modern politics. Loudly, because the implications stretch across oceans, decades, and legal systems. Britain agreed to hand sovereignty over the Chagos Islands to Mauritius, while keeping the most important island under a 99-year lease. On paper, a colonial wrong was acknowledged. In practice, a military reality stayed firmly in place.

Keir Starmer described the deal as unavoidable. According to him, there was no realistic path that preserved security while ignoring international law. That phrase, no alternative, carried a remarkable amount of weight. It suggested inevitability, responsibility, even adulthood. At the same time, it sidestepped the uncomfortable truth that this arrangement emerged from years of legal pressure, diplomatic unease, and strategic anxiety rather than sudden necessity.

The headline number did its job immediately. £3.4 billion. Large enough to sound decisive, abstract enough to feel unreal. Spread across nearly a century, however, it becomes roughly £101 million a year. Consequently, the deal starts to resemble a subscription fee for global relevance. Pay annually, retain the runway, keep the radar humming.

At the centre of the story sits Diego Garcia, whether officials prefer to acknowledge it or not. It is the largest island in the archipelago and one of the most strategically valuable military outposts on the planet. From this strip of coral and concrete, the United States and the United Kingdom have projected power across the Middle East, East Africa, and the wider Indo-Pacific. Bombers pass through. Surveillance aircraft rotate in and out. Logistics and communications hum quietly in the background.

Calling it a lease undersells the emotional reality. Britain is formally giving back territory it should arguably never have separated from Mauritius in the first place. Yet it retains functional control of the only island that truly matters to security planners. Sovereignty changes hands. Access does not.

To understand how Britain arrived here, it helps to rewind to the late 1960s. As the Cold War intensified, the United States sought a foothold in the Indian Ocean. Britain responded by removing the Chagos Islands from Mauritius before Mauritian independence. The territory was rebranded as the British Indian Ocean Territory. Meanwhile, the inhabitants, later known as the Chagossians, were gradually and forcibly removed.

Dogs were killed. Homes were abandoned. Families were shipped to Mauritius, the Seychelles, and eventually the UK itself. For decades, Britain maintained that this was regrettable but necessary. Security demanded sacrifice. Strategy required silence. Nevertheless, Chagossians continued to fight in British courts, international forums, and public opinion. They lost more cases than they won, but they never disappeared.

The legal tide began to turn in the late 2010s. In 2019, the International Court of Justice issued an advisory opinion stating that Britain’s continued administration of the islands was unlawful. Shortly afterwards, the UN General Assembly backed that view. Britain responded with polite defiance. Advisory opinions were noted. Resolutions were acknowledged. Nothing changed.

Gradually, though, circumstances shifted. Brexit altered Britain’s diplomatic posture. Global alliances became more transactional. At the same time, China expanded its presence across the Indian Ocean through ports, loans, and naval visits. As a result, the idea that Britain could indefinitely ignore international legal consensus while defending a rules-based order became harder to sustain.

Negotiations with Mauritius began under a Conservative government in 2022. They continued through eleven rounds, spanning elections, leadership changes, and shifting geopolitical concerns. When Labour took power, the process accelerated rather than reversed. By May 2025, the outlines of a deal were ready.

Under its terms, Mauritius would receive sovereignty over the entire archipelago. Britain would retain long-term rights over Diego Garcia, with options to extend. Britain would also pay Mauritius billions over the life of the agreement. Meanwhile, the US base would remain untouched. Officially, at least, the legal dispute would be resolved.

Supporters described the outcome as pragmatic. Critics, however, called it extortion wrapped in diplomacy. Some asked why Britain was paying to keep something it already controlled. Others countered that without a deal, Britain risked losing the base entirely as pressure mounted.

Domestic politics ensured the agreement did not pass quietly. In Parliament, the House of Lords inflicted multiple defeats on the implementing legislation. Peers demanded clearer financial oversight and questioned the scale of long-term commitments. Conservative leader Kemi Badenoch accused the government of weakness, warning that Mauritius’s economic closeness to China could turn a settlement into a liability.

As the debate intensified, the language sharpened. Reform UK framed the deal as a symbol of national decline. Commentators questioned why billions could be found offshore while domestic budgets tightened. Ministers responded by invoking national security, alliance obligations, and the risks of leaving legal vacuums for rivals to exploit.

Then US President Donald Trump entered the conversation, as he tends to do. In early 2026, he publicly derided the agreement as stupidity and weakness. At the same time, he linked it to his renewed interest in acquiring Greenland. The comparison sounded surreal. Even so, the underlying message felt familiar. Territory matters. Bases matter. Great powers do not apologise unless forced.

Downing Street brushed off the comments. Officials reaffirmed support for Denmark and dismissed Trump’s remarks as political theatre. Nonetheless, the episode exposed how fragile consensus can become when long-term treaties collide with short-term political egos.

While politicians traded soundbites, the Chagossians watched again from the margins. The deal included commitments to support their community and preserve cultural heritage. Even so, the details remain disputed. Crucially, it did not include a guaranteed right of return to Diego Garcia. Instead, the framework envisages possible resettlement on other islands, subject to feasibility and environmental limits.

For some Chagossians, the agreement felt like overdue recognition. Britain had acknowledged wrongdoing. Sovereignty had shifted. The conversation had moved. For others, it felt like another transaction conducted overhead, their displacement acknowledged but unresolved.

Environmental concerns added another layer of tension. The islands sit within one of the world’s largest marine protected areas. Coral reefs, fish species, and fragile ecosystems dominate the surrounding waters. Consequently, conservationists fear that resettlement or development could cause irreversible damage.

At the same time, critics note that military activity has hardly been ecologically neutral. Runways, fuel storage, waste systems, and naval traffic leave their own marks. Therefore, the idea of pristine isolation only tells part of the story.

Mauritius now faces a delicate balancing act. Sovereignty brings prestige, symbolism, and legal clarity. However, it also brings responsibility. Managing relations with Britain, the United States, China, and regional neighbours will require careful diplomacy. The base cannot simply be wished away.

For Britain, the deal represents a peculiar form of post-imperial adjustment. It is neither a clean break nor a full reckoning. Instead, it resembles a structured exit that leaves the furniture exactly where it was. The flag may change. The function remains.

This is not how decolonisation was once imagined. There are no jubilant ceremonies. There are no mass returns. Instead, there are leases, clauses, extensions, and oversight mechanisms. Sovereignty becomes transferable while operational reality stays put.

Perhaps that is the defining feature of modern power. Control no longer requires ownership. Influence no longer needs flags. What matters instead are access rights, legal frameworks, and logistical continuity.

Somewhere in the Indian Ocean, Diego Garcia continues its routine. Aircraft land. Satellites listen. Personnel rotate. The island does what it has always done, largely unseen by those debating its future from afar.

Britain has accepted that it cannot indefinitely defend colonial arrangements that contradict international law. At the same time, it has ensured that its strategic footprint remains intact. Whether that balance holds for a century remains uncertain.

The Chagos deal will not fade quickly. It touches nerves about empire, identity, money, law, and security. Ultimately, it forces uncomfortable questions about what sovereignty means in a world shaped by alliances and bases.

Sovereignty has been ceded. Rent is being paid. The runway remains open. Once again, the real story sits between moral reckoning and strategic convenience, written not in speeches but in clauses that will outlive the people who signed them.