The Agreement between the United Kingdom and the Republic of Mauritius concerning the Chagos Archipelago including Diego Garcia was signed in London and Port Louis on 22 May 2025 by Prime Ministers Keir Starmer and Navin Ramgoolam, in two originals in English. It is not General Assembly resolution 73/295, nor the 2019 advisory opinion of the International Court of Justice, which the preamble has regard to. An exchange of notes deemed the date of signature to be that of the virtual ceremony. The instrument was laid before the British Parliament as Mauritius No. 1 (2025), CP 1334. It is not in force.

The preamble recognises the wrongs of the past, recalls the treatment of Chagossians and the need to complete the decolonisation of Mauritius, and seeks a full and final resolution of the differences. Article 1: Mauritius is sovereign over the Chagos Archipelago in its entirety, including Diego Garcia. Article 2: as sovereign, Mauritius authorises the United Kingdom to exercise the rights and authorities required for the long-term operation of the Base, according to the annexes; Mauritius retains title over the land and territorial sea and the rights not so authorised, including natural resources. No military-base protocol is transcribed.

Article 5 ties the United Kingdom’s exercise of authority to international environmental law and to support for a Mauritian marine protected area, by a separate instrument. Article 6: Mauritius is free to implement a programme of resettlement on the islands of the Archipelago other than Diego Garcia, in conformity with the Agreement and the laws of Mauritius. Article 11 provides an economic partnership: an annual sum, capitalisation of a trust fund for Chagossians and a twenty-five-year development framework; the details are in an exchange of letters. The Agreement is the full and final settlement of Mauritius’s claims in relation to the Archipelago.

Article 13: an initial duration of ninety-nine years from entry into force, with a possible further forty years if the Parties agree the conditions no later than two years before expiry. Article 18: it enters into force on the first day of the first month following receipt of the later note by which the Parties notify completion of their internal procedures, unless they agree otherwise. At the time this article was published, that exchange of notes had not taken place. The annexes on defence, jurisdiction, the Joint Commission and arbitration remain at the level of framework; they are not transcribed.

Cover: Government House in Port Louis, one of the places of signature; we do not claim the hall and we do not use images of the base. Wikimedia Commons, free licence.

Sources consulted: Agreement concerning the Chagos Archipelago including Diego Garcia; Agreement concerning the Chagos Archipelago including Diego Garcia (UK Treaty Series, Mauritius No. 1, 2025).