In justifying Greenland bid, why Trump cited the Indian Ocean island of Diego Garcia

What are the Chagos Islands, where Diego Garcia is located?

In October 2024, the UK government announced it would cede sovereignty of the strategically important Chagos Islands to Mauritius, calling it a “historic political agreement”. The UK has long controlled Chagos and the Diego Garcia military base located there, jointly operating it with the United States.

The Chagos archipelago, comprising 58 islands, lies roughly 500 km to the south of the Maldives archipelago in the Indian Ocean. These islands were uninhabited until the late 18th century, when the French brought in slave labour from Africa and India to work in newly established coconut plantations. In 1814, France ceded the islands to the British.

Diego Garcia and Chagos.

In 1965, the UK constituted the British Indian Ocean Territory (BIOT), which included the Chagos Islands. A few other BIOT islands were later ceded to the Seychelles in 1976 after it gained independence from Britain.

Chagos was attached to Mauritius, another British colony in the Indian Ocean, for administrative purposes. But when Mauritius gained independence in 1968, Chagos remained with Britain. The UK government gave the newly independent country a grant of 3 million pounds over the “detachment” of the Chagos archipelago.

And what is the significance of Diego Garcia?

In 1966, Britain signed an agreement with the US, which made the BIOT available for the two countries’ defence needs. Land was acquired in 1967, and four years later, the plantation on Diego Garcia — the largest in the archipelago — was shut down.

Behind Britain retaining sovereignty over the Chagos Islands was its strategic location. Given the importance of the Middle East for the US, maintaining a presence in the Indian Ocean was critical. Establishing a base at Diego Garcia also gave the Americans an outpost to monitor the Malacca Strait, a chokepoint for global trade that is especially vital to China.

A press release from the UK government said, “Its deep-water port, airfield, and advanced communications and surveillance capabilities give the UK and its allies crucial strategic capabilities, which have played a key role in missions to disrupt high-value terrorists, including Islamic State threats to the UK.”

The BIOT administration then enacted an Immigration Ordinance, which made it unlawful for a person to enter or remain in Diego Garcia without a permit, and enabled the removal of those who remained on the island. Around 2,000 civilians were subsequently kicked out — an issue that has been central to the dispute between the UK and Mauritius.

Diego Garcia became a fully operational military base in 1986. According to an article in the Foreign Policy magazine, “Thanks to its vital location, the island houses a military base that served as a critical node for American air operations during the Gulf War and the wars in Iraq and Afghanistan. Post-9/11, it has also been allegedly used as a detention centre by the [US intelligence agency] CIA.”

Following the UK’s announcement in 2024, then US President Joe Biden said, “Diego Garcia is the site of a joint U.S.-UK military facility that plays a vital role in national, regional, and global security. It enables the United States to support operations that demonstrate our shared commitment to regional stability, provide rapid response to crises, and counter some of the most challenging security threats we face.”

So why did the UK give away Diego Garcia?

Mauritius has long claimed that the UK illegally occupies Chagos, and has raised the matter in international fora. A few years ago, negotiations began between the governments of the UK and Mauritius for the future of the Chagos Islands.

In 2017, the UN General Assembly voted to ask the International Court of Justice to examine the legal status of the Chagos archipelago. Two years later, the UNGA adopted a resolution welcoming an ICJ advisory opinion, demanding that the United Kingdom “unconditionally withdraw its colonial administration from the area within six months”.

Then ICJ President Abdulqawi Ahmed Yusuf had said the detachment of the Chagos archipelago in 1965 from Mauritius was not based on a “free and genuine expression of the people concerned”. Chagossians today live in the UK, Mauritius and Seychelles.

Under the agreement, the UK has ceded claims over the islands, and Mauritius is now “free to implement a programme of resettlement on the islands of the Chagos Archipelago, other than Diego Garcia”. The UK has also promised to create a new trust fund “for the benefit of Chagossians.” However, the agreement allows the Diego Garcia base to remain operational for an “initial period” of 99 years, while giving sovereignty to Mauritius, at an annual cost of around 101 million pounds.

The resolution of the dispute has broader implications. As the Foreign Policy article noted: “A successful resolution to the Diego Garcia spat would affirm Western commitment to a free and open Indo-Pacific. If left unresolved, however, the issue could drive countries such as Mauritius to seek redress with alternative partners like China.”

Still, some criticised the deal for potentially allowing China a greater presence around the island. Members of the Chagossian diaspora have also lamented Mauritius gaining control and demanded the right to self-determination.

As a nation formerly colonised by Britain, India has maintained steadfast support for Mauritius’ claims over the Chagos Islands, and welcomed the deal. It voted in favour of the island country at the UNGA in 2019. In recent years, India has attempted to deepen its ties with Mauritius amidst China’s ever-increasing assertiveness in the Indian Ocean. In 2024, an India-built airstrip and a jetty were inaugurated at Agaléga, a two-island dependency of Mauritius in the Western Indian Ocean.

Why did Trump recall Diego Garcia?

It is unclear why Trump referred to Diego Garcia now, although there have been minor developments in the matter.

Notably, after UK Prime Minister Keir Starmer met Trump in February 2025, he said of the deal, “We’re going to have some discussions about that very soon, and I have a feeling it’s going to work out very well.” In April that year, he was reported to have formally signed off on the deal. The agreement between the UK and Mauritius was signed in May 2025.

The UK then introduced the Military Base and British Indian Ocean Territory Bill of 2024-25, to enact parts of that agreement. The House of Commons was scheduled to consider certain amendments to the Bill on January 20 this year.

This story includes parts of an explainer first published in 2024.