Andy Burnham doubles down on controversial Chagos ‘surrender’

Prime Minister Andy Burnham has reaffirmed his determination to find a way forward on the disputed Chagos Islands agreement, despite continued uncertainty over the position of the United States and the future of the UK-US military base on Diego Garcia.

The issue has become one of the most sensitive foreign-policy challenges facing Burnham’s government, with the Prime Minister now seeking to maintain the agreement with Mauritius while also addressing American concerns over the strategic implications of the arrangement.

Speaking to reporters while travelling to New York for the United Nations General Assembly, Burnham said he remained committed to finding a resolution.

The Prime Minister had spoken with Mauritian Prime Minister Navin Ramgoolam before travelling to the UN summit. Downing Street said the two leaders agreed to remain in close contact, while Burnham expressed the hope that the British and Mauritian foreign ministers could meet during the General Assembly.

The latest intervention comes as the agreement remains unratified by the UK Parliament and negotiations continue with both Mauritius and the United States.

What the Chagos agreement actually does

The dispute centres on the future sovereignty of the Chagos Archipelago, which has been administered by Britain as the British Indian Ocean Territory since the 1960s.

Under the agreement signed by the UK and Mauritius in May 2025, Mauritius would exercise sovereignty over the entire archipelago.

At the same time, the agreement provides the UK with extensive rights concerning Diego Garcia, the largest island and the location of the strategically important joint UK-US military facility.

The arrangement provides for an initial 99-year period during which the UK would retain the rights and authorities necessary to operate the base. The agreement also allows for a possible further extension under its terms.

The government has consistently argued that the central purpose of the treaty is to protect the long-term operation of Diego Garcia.

Defence Secretary John Healey said when the treaty was signed in May 2025 that it would guarantee continued UK control of the military base for the next 99 years and beyond.

That is why the government rejects the description that the agreement simply amounts to abandoning the strategically important territory.

The political dispute instead centres on whether transferring sovereignty while leasing operational rights represents an appropriate way of securing the base.

Why Diego Garcia matters

Diego Garcia occupies a strategically important position in the Indian Ocean.

The joint UK-US military facility has been used for decades as a logistics and military-support hub. The British Government describes it as crucial to UK and allied security.

In a recent parliamentary answer, Defence Minister Luke Pollard said the base was “crucial” to the security of Britain and its key allies and said maintaining long-term operational control was the entire basis for the UK-Mauritius agreement.

The strategic importance of Diego Garcia explains why the United States has been closely involved in discussions surrounding the treaty.

The UK government previously said the United States had supported the agreement when it was signed. US Secretary of State Marco Rubio welcomed the deal in May 2025, saying it secured the long-term operation of the joint US-UK military facility.

The situation has subsequently become more complicated following opposition from Donald Trump.

Reuters reported that Trump has described the agreement as a “big mistake”, while the legislation required to implement the treaty has not yet been completed.

That has left Burnham attempting to bridge two relationships that are both important to the British government: its agreement with Mauritius and its strategic relationship with Washington.

Burnham’s latest message to Mauritius

Burnham’s conversation with Ramgoolam indicates that London is not simply abandoning the treaty.

Downing Street said Burnham underlined his commitment to working with Mauritius and the United States to find a way forward that secures the operation of Diego Garcia and protects Britain’s national security.

That wording is significant.

It suggests that the government’s immediate objective is not necessarily to proceed with the existing agreement unchanged, but to find a solution acceptable to the relevant parties.

The treaty itself cannot currently be treated as fully implemented.

The government has repeatedly stated that it will continue discussions with both Mauritius and the US before ratification.

In September, Foreign Office minister Uma Kumaran told Parliament that Britain would continue working with Washington and Mauritius “to find a way forward that is in the UK’s best interests and protects our national security”.

Another parliamentary answer confirmed that the UK government had always been clear that the US must be content with the agreement before Britain proceeds with ratification.

The financial argument

One of the most contentious aspects of the agreement is its financial cost.

Under the treaty, Britain would pay Mauritius an average of approximately £101 million a year over the initial 99-year period, measured in 2025/26 prices. The House of Commons Library estimates the total at around £3.4 billion.

Opponents have highlighted the long-term financial commitment and questioned whether Britain should pay for continued use of a military facility that has historically been operated without a comparable lease payment.

The government has defended the arrangement as the cost of securing the base’s long-term future.

The House of Commons Library notes that ministers have argued the cost represents less than 0.2 percent of the UK’s annual defence budget and is consistent with the broader practice of paying to maintain overseas military bases.

The government has also confirmed that payments would not begin until the treaty has been ratified.

A parliamentary answer on September 14 stated that the value of the payments had not changed and that no payments were due under the agreement before ratification.

Why opponents remain concerned

Conservative politicians have consistently criticised the treaty.

Their objections include the financial cost, the transfer of sovereignty to Mauritius and concerns over the long-term security environment surrounding Diego Garcia.

The House of Commons Library records Conservative opposition to the agreement, including arguments that the cost is unacceptable and concerns about Mauritius’ international relationships.

The controversy also extends beyond the immediate question of Diego Garcia.

Some British politicians have raised concerns about what the agreement could signal regarding other disputed British territories, particularly the Falkland Islands.

Those are political arguments rather than consequences established by the treaty itself. The Chagos Islands and Falkland Islands have different histories, legal circumstances and geographic situations.

The UK government has nevertheless faced questions about whether decisions over one overseas territory could affect wider perceptions of British sovereignty.

The Chagossian dimension

There is another part of the agreement that is sometimes overlooked in the political debate: the Chagossians themselves.

The Chagos Islanders were removed from the archipelago between 1968 and 1973 to facilitate the establishment and operation of the military base on Diego Garcia.

The 2025 treaty recognises provisions concerning the rights of Chagossians and their descendants to return to parts of the archipelago.

Under the agreement, Mauritius would be able to arrange resettlement on the islands other than Diego Garcia. Mauritius would also establish a marine protected area, with British support.

For Mauritius, sovereignty over the Chagos Archipelago is presented as part of completing the country’s decolonisation process.

For Britain, the government has argued that the treaty provides a way of addressing the historical dispute while guaranteeing the military base’s future.

These competing perspectives are central to understanding why the issue has proved politically difficult.

Parliament still has a role

The agreement was formally laid before Parliament in May 2025.

Under the Constitutional Reform and Governance Act, Parliament had a scrutiny period during which either House could resolve against ratification. Two early-day motions opposing ratification were tabled in June 2025, including one sponsored by Conservative leader Kemi Badenoch that attracted 107 signatures. The motions did not themselves require a Commons debate or vote under the treaty scrutiny process.

The treaty therefore remains an issue requiring political and parliamentary handling rather than being a completed transfer of sovereignty.

Recent parliamentary answers indicate that discussions are continuing.

In September, ministers said financial decisions connected with the treaty would be handled through the Ministry of Defence’s normal financial planning process. They also reiterated that negotiations with the US and Mauritius remained ongoing.

The Trump factor

The most immediate complication for Burnham is the American position.

The UK-US military relationship is central to the operation of Diego Garcia. Even though the British government argues that the treaty protects the base, Washington’s concerns mean that London cannot simply treat the agreement as a bilateral arrangement with Mauritius.

Burnham’s planned meeting with Trump in New York therefore carries particular diplomatic significance.

The Prime Minister’s public position is that he wants to work with both countries to reach an arrangement that preserves the military facility and protects Britain’s security interests.

That approach also explains why ministers have avoided presenting the current disagreement as a final breakdown.

The government’s latest statements consistently describe discussions as ongoing.

A deal still awaiting its final chapter

For Burnham, the Chagos dispute has therefore become a test of how his government balances international law, Britain’s relationship with Mauritius and the United States, defence requirements and the political controversy surrounding sovereignty.

Calling the agreement a “surrender” is a description used by opponents rather than a neutral description of its legal structure.

The actual arrangement would transfer sovereignty over the Chagos Archipelago to Mauritius while providing Britain with long-term rights and operational control over Diego Garcia. The government argues that this structure provides the most secure route for preserving the military base.

The unresolved question is whether Washington will ultimately be satisfied with the arrangements and whether the British government can secure a political and legal path towards ratification.

Burnham’s latest comments suggest he intends to keep negotiating rather than abandon the agreement.

The Prime Minister has now publicly committed himself to working with Mauritius and the United States to find a resolution.

Until those discussions are completed and Parliament is able to move towards ratification, however, the future legal status of the Chagos Islands remains unsettled.

For a government that has repeatedly presented Diego Garcia as a vital strategic asset, the next stage of the negotiations will determine whether Burnham can reconcile the sovereignty agreement with the security concerns that have placed the treaty under renewed international scrutiny.