Downing Street has defended the treaty transferring sovereignty of the Chagos Archipelago to Mauritius while preserving long‑term operation of the joint US‑UK facility on Diego Garcia. The response follows President Donald Trump’s post describing the arrangement as “great stupidity” and “total weakness”, which No.10 countered by pointing to prior United States support and the agreement’s security provisions. The treaty was signed on 22 May 2025. (apnews.com)
The published treaty confirms Mauritius’ sovereignty over the archipelago while authorising the UK to exercise the rights and authorities needed to operate the base on Diego Garcia for an initial 99‑year term, with options to extend. The government will make indexed annual payments averaging £101m in 2025/26 prices-an estimated net total of about £3.4bn over the initial period-an estimate verified by the Government Actuary’s Department. (commonslibrary.parliament.uk)
Ministers argue the agreement was necessary to protect base operations after a series of international legal rulings eroded the UK’s position. The International Court of Justice’s 25 February 2019 advisory opinion and the UN General Assembly’s Resolution 73/295 urged the UK to end its administration, while the Special Chamber of ITLOS in 2021 and 2023 treated Mauritius as sovereign for the purposes of maritime delimitation. Officials say resolving sovereignty removes future legal risks to the base. (icj-cij.org)
US backing has been recorded repeatedly. The Pentagon publicly welcomed progress in 2024, and on 22 May 2025 Secretary of State Marco Rubio said Washington welcomed the treaty because it secures the “long‑term, stable, and effective” operation of the facility. Those statements remain the government’s reference point despite the President’s remarks this week. (defense.gov)
UK ministers had already acknowledged Washington’s role in the final approach. In February 2025, the Foreign Secretary said the deal would not proceed without US support, and later that month the President said he was inclined to “go along” with the UK’s approach during talks at the White House. (itv.com)
Parliamentary scrutiny is advanced but not complete. The Diego Garcia Military Base and British Indian Ocean Territory Bill passed Lords third reading on 12 January 2026 and now returns to the Commons to consider Lords amendments. Under the Constitutional Reform and Governance Act 2010 the 21 sitting days for opposing ratification elapsed on 3 July 2025, but the government has said it will ratify only once domestic legislation is in place. (parliament.uk)
Peers recorded concerns but did not block progress. At third reading the House of Lords agreed a non‑binding regret motion highlighting costs and seeking clarity on security assurances and Chagossian engagement. The bill itself continues, with Commons consideration of Lords amendments the next step. (parliament.uk)
Mauritius has reiterated that the treaty was concluded bilaterally with the UK and that sovereignty is already recognised in international law. Mauritius’ Attorney General, Gavin Glover, said the issue should “no longer be subject to debate”, responding to US criticism by underlining the agreement’s legal basis. (yahoo.com)
Chagossian views remain divided and central to implementation. Two British Chagossians, Bertrice Pompe and Bernadette Dugasse-both born on Diego Garcia-secured a temporary High Court injunction hours before the signing, which was lifted the same day. Their concerns focus on exclusion from talks and the lack of a right of return to Diego Garcia. The treaty allows Mauritius to organise resettlement on other islands and is accompanied by a UK‑capitalised £40m Chagossian Trust Fund with majority Chagossian governance. (news.sky.com)
Operational safeguards feature in the treaty text and related documentation. Mauritius commits that no other state will use the outer islands without UK agreement; the arrangement preserves access, maintenance and investment for the base over the initial 99 years, with extension options. UK officials say this protects capabilities and deters hostile interference. (commonslibrary.parliament.uk)
Allies have previously indicated support. UK statements cite backing from partners including the United States and other Five Eyes members, mirroring public US endorsements in May 2025. That context, ministers argue, means the treaty strengthens rather than weakens collective security. (npr.org)
Next steps hinge on completing UK legislation and Mauritius’ domestic processes for ratification. For departments, the immediate work is to finalise secondary instruments, publish cost disclosures required by recent Lords amendments, and stand up the trust fund arrangements. The government maintains its position is unchanged and that the agreement will secure the base for decades. (parliament.uk)