Sovereignty over the Chagos Islands — Strategic, Legal, and Ethical Risks of Surrender

UK Sovereignty over the Chagos Islands — Strategic, Legal, and Ethical Risks of Surrender.

Published: 22 May 2025

Update 12 June 2025

Strategic & Security Concerns

Conservative MP Kemi Badenoch stated in PMQs that she received a security briefing on the Chagos deal and described it as an “immoral surrender,” warning that “when Labour negotiates, our country loses” and accusing the Prime Minister of exchanging “money that belongs to our children and their children” youtube.com+10politics.co.uk+10linkedin.com+10. She also demanded that “not a penny” of the defence budget be used to fund it, highlighting fears the extra cost would divert vital military resources

Financial Impact

The annual £101 million lease deal, totalling roughly £10 billion over 99 years, continues to draw criticism. Badenoch highlights this as a burden on UK taxpayers, contrasting the high cost with Mauritius’s use of the funds to implement tax cuts and reduce national debt.

Summary

On May 22, 2025, the UK finalised an agreement to cede sovereignty of the Chagos Islands to Mauritius. The deal includes a 99-year lease of Diego Garcia to the UK at a cost of £101 million per year, raising concerns over national security, financial prudence, and potential conflicts of interest. Despite significant political pressure, the UK remains under no legal obligation to surrender the territory. This briefing evaluates the drivers behind the decision, associated risks, and potential improprieties.

Sources of Pressure to Cede Sovereignty

International Court of Justice (ICJ) – Issued a 2019 advisory opinion (non-binding) declaring the UK’s continued administration of Chagos as unlawful and urging its return to Mauritius.
UN General Assembly (UNGA) – Adopted Resolution 73/295, politically—but not legally—urging the UK to withdraw.
Mauritius, African Union & Global South – Frame the issue through a decolonisation lens and apply diplomatic pressure.
NGOs & Human Rights Groups – Support the return of Chagossians, frequently linking the cause to broader post-colonial justice movements.

Note: None of these entities can legally compel the UK to act. Their influence is political and reputational only.

Legal Position

The UK has administered the Chagos Archipelago since 1814, first via Mauritius (a colonial dependency) and then directly as the British Indian Ocean Territory (BIOT) since 1965.
Mauritius never exercised sovereign control over Chagos as an independent state.
The ICJ opinion and UNGA resolution are non-binding under international law.
There is no treaty, ruling, or domestic legal mechanism obliging the UK to relinquish sovereignty.
Precedent risk: Surrendering Chagos under international pressure may weaken the UK’s global territorial claims, notably in Falklands and Gibraltar.

Strategic and Security Risks

Geopolitical Concerns: Mauritius is strengthening ties with Russia and the Chinese Communist Party (CCP)—both strategic adversaries of the UK and its allies.
Loss of Control: Chagos, particularly Diego Garcia, is a critical Western military asset in the Indian Ocean. It is used for:
- Long-range strike operations
- Submarine activity and nuclear deterrence
- Surveillance across the Middle East, Africa, and Asia
Future Access Vulnerability: Although a 99-year lease is agreed, a shift in Mauritian policy could:
- Terminate or restrict UK/US access
- Invite dual-use Chinese infrastructure, as seen in Djibouti and Sri Lanka
- Allow BRICS/CCP-aligned powers into the region, undermining NATO interests

Conflict of Interest and Questionable Decisions

Philippe Sands KC, a close associate of PM Keir Starmer, has acted as the chief legal adviser to Mauritius on Chagos sovereignty since 2010.
Sands has represented Mauritius at the ICJ and other international tribunals, advocating for UK withdrawal.
He has also engaged in symbolic acts supporting Mauritian sovereignty, such as raising the Mauritian flag on Chagos territory without UK permission.
Critics argue that Starmer’s subsequent decision to approve the sovereignty transfer raises serious questions of conflict of interest, given his longstanding professional association with Sands.
No formal review or public disclosure has addressed whether Sands had undue influence over policy or whether Starmer considered recusal or ethical guidance before proceeding.

Financial Implications

The UK will pay £101 million annually for 99 years to lease back military access—a cost totalling £10 billion over the term.
The deal has drawn criticism amid broader public spending cuts and may represent a poor return for relinquishing strategic territory that was previously cost-free in sovereign terms.

Conclusion and Recommendation

The UK faces no legal requirement to cede the Chagos Islands.
The decision is entirely political and appears driven by diplomatic appeasement and internal conflicts of interest, not national interest.
The strategic, financial, and sovereignty costs of surrendering Chagos outweigh any perceived reputational benefits.
Given Mauritius’s increasing ties with Russia and China, the risk of long-term loss of military access and strategic presence in the Indian Ocean is high.

Given the strategic importance of the Chagos Islands and the serious questions surrounding the recent sovereignty transfer, there is a clear case for greater parliamentary scrutiny and an independent investigation into potential conflicts of interest. The involvement of Philippe Sands KC—a long-time legal adviser to Mauritius and close associate of Prime Minister Keir Starmer—in advocating for the handover raises legitimate concerns about impartiality and due process. If the agreement was concluded via executive action rather than legislation, it remains constitutionally reversible, particularly if ratification is incomplete. Even if passed through Parliament, future repeal or renegotiation is politically feasible. Moreover, national security concerns, the £101 million-a-year lease deal, and the lack of full parliamentary oversight strengthen the case for a formal review. Reversal mechanisms such as judicial review, a public inquiry, or legislative action could still be pursued—especially if evidence emerges of procedural flaws or compromised UK interests. At a minimum, implementation should be frozen pending a full review of the legal status, financial implications, and any improper influence in the decision-making process.

“James Cartlidge, a former defense minister, labeled the agreement a “total, abject surrender of our territory and a fundamental betrayal of the U.K. national interest.” He emphasised that the deal undermines national security by compromising control over a strategic military asset .