New Delhi: India welcomed the agreement between the United Kingdom and Mauritius on the transfer of sovereignty over the Chagos Islands, calling it a milestone in completing the Indian Ocean island nation’s decolonisation “in the spirit of international law and a rules-based order.”

On May 23, UK Prime Minister Keir Starmer announced that the deal had been finalised – seven months after an initial understanding was reached – to transfer the Chagos Islands to Mauritius, which will then lease back only the largest island, Diego Garcia, for £101 million a year to enable joint operation of the military base located there.

India, which had consistently supported Mauritius’s campaign to get back Chagos, welcomed the signing of the deal. “The formal resolution of the longstanding Chagos dispute through this bilateral treaty is a milestone achievement and a positive development for the region,” said a statement issued by Ministry of External Affairs.

The agreement, it noted, builds on the understanding reached in October 2024 and “marks the culmination of the process of decolonisation of Mauritius in the spirit of international law and rules-based order”.

The statement also sought to remind that India had always supported Mauritius’ claim “in keeping with its principled position on decolonisation, respect for sovereignty, and the territorial integrity of nations”.

Highlighting the strategic importance of the region, India said the security of the Indian Ocean would remain a priority. “As a steadfast and longstanding partner of Mauritius, India remains committed to working closely with Mauritius and other like-minded countries to strengthen maritime security and regional stability, and ensure peace and prosperity in the Indian Ocean region,” the statement said.

Trump and India

In 2017, the United Nation General Assembly had passed a resolution asking UN’s principal judicial organ, the International Court of Justice to give an advisory opinion on whether the UK’s continuing occupation of the islands in the Indian Ocean was valid under international law.

As The Wire had reported then, senior members of the first Trump administration had asked India to lean on its ally, Mauritius to withdraw the UNGA resolution. While India had demurred that it would be not in line with its long-standing policy, New Delhi had also nudged Mauritius government to make it explicitly clear at that stage that it was not seeking the removal of the military base at Diego Garcia.

India not only made a written submission, but also made an oral intervention during the public hearings before the ICJ. 

The Chagos Archipelago was carved away from Mauritius as “British Indian Ocean Territory” in 1965, when it was still a colony. The British government gave Diego Garcia on a long lease to the US in 1966, and forcibly evicted all its inhabitants. Mauritius became and independent nation in 1968.

In its written submission, India made it clear that it backed the Mauritian interpretation leaders of the Indian Ocean island nation gave their assent to the 1965 agreement under duress. “British Cabinet papers, at the time of detachment of the Chagos Archipelago, reveal that Mr Harold Wilson, the prime minister, informed the Mauritian Premier in September 1965 that part of the price for independence was Mauritius’s assent to the detachment of the Chagos”.

The ICJ ruled against the UK’s control of the islands in February 2019 and ordered London to hand it back “as rapidly as possible”. This legal opinion was in addition to the March 2015 ruling of the Permanent Court of Arbitration which held that marine protected area that UK had declared around Chagos was in violation of international law. 

Following the ICJ order, the UNGA, with 116 ayes, voted in another resolution that UK should hand back the archipelago to Mauritius within six months. 

An agreement

In October last year, UK and Mauritius prime ministers jointly announced that the UK was giving up sovereignty of the Chagos islands and that a final treaty will be completed as quickly as possible.

Under the terms of the agreement, UK will pay Mauritius £101 million annually to lease back Diego Garcia for at least 99 years. There is also a provision to extend the lease for 40 years. Further, UK would have a veto on any structure or building within 24 nautical miles of the island.

A £40 million trust fund has been established for displaced residents and Mauritian development.

As per a clause of the treaty, UK would have to “expeditiously” inform Mauritius of any attack on a third party launched from Diego Garcia. 

At a press conference to explain the rationale behind the deal, UK Prime Minister Keir Starmer said London had little choice but to pursue a sovereignty agreement, warning that failure to do so would likely result in legal defeats at international forums, potentially rendering the base inoperable.

“Even if we chose to ignore judgments made against us, international organisations and other countries would act on them,” said Starmer.

He cited the example of the electromagnetic spectrum, which countries have the sovereign right to manage within their territories. “The use of spectrum is key to understanding and anticipating those who seek to do us harm. If our right to control it is put into doubt, we would lose the first line of defence against other countries who wish to interfere and disrupt this capability,” he explained.

China and other politics

Starmer further warned that if the UK had refused to enter into this agreement, the resulting legal uncertainty could have opened the door for China or other nations to establish their own bases on the outer islands of the Chagos Archipelago.

The agreement was nearly derailed by a last-minute legal challenge in the early hours of Thursday, filed by a UK citizen of Chagossian descent. However, the high court dismissed the injunction within hours, clearing the way for the treaty to be signed.

The United States Secretary of State Marco Rubio welcomed the agreement, stating that it was necessary for the long-term viability of the military base.

“Following a comprehensive interagency review, the Trump Administration determined that this agreement secures the long-term, stable, and effective operation of the joint US-UK military facility at Diego Garcia. This is a critical asset for regional and global security.  President Trump expressed his support for this monumental achievement during his meeting with Prime Minister Starmer at the White House,” he said in a statement.

The agreement has drawn sharp criticism within the United Kingdom, with the opposition Conservative and Reform UK parties objecting to the handover of the sovereignty of the military base to a country they claim has close ties to China.

Conservative Leader Kemi Badenoch referred to Mauritius as “an ally of China,” while Reform UK’s Nigel Farage was quoted by The Guardian as saying that the decision to cede control of the Chagos Islands to Mauritius “plays into China’s hands.”

Mauritius, however, has been strategically allied with India since its independence. With 65–70% of its population of Indian origin, the island nation is a key regional partner for New Delhi. 

Last year, the prime ministers of India and Mauritius jointly inaugurated an airstrip and jetty on the remote island of Agalega, seen as critical for enhancing maritime surveillance. Mauritius is also among the largest recipients of India’s development assistance.

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