UK signs  £101 million-a-year deal to hand over Chagos Island, a Joint UK-US military base in the archipelago , Diego Garcia, to Mauritius. The British government felt that without ceding sovereignty to Mauritius, the operation of the base would become unworkable which would pose a great threat to UK security. Defence Secretary John Healey told MPs that “without this deal, within weeks, we could face losing legal rulings and within a few years the base would become inoperable”.

US Secretary of State Marco Rubio said “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”.

Their legal challenge is based on a series of judgements by various United Nations bodies that the Chagos Islands belong to Mauritius and UK had no legal right to separate the islands from Mauritius before the former British colony became independent in the 1960s. In 2019 there was an “advisory opinion” by the UN’s International Court of Justice backed up by a later ruling of the Special Chamber of the International Tribunal for the Law of the Sea, which would soon become a legally binding judgement by this UN tribunal. “The most proximate, the most potentially serious, is the tribunal of the International Convention of the Sea”. If the UK government lost a case there, ministers argue, the outside world would be obliged by law to take decisions that would interfere in the ruling of the base and Diego Garcia’s satellite communications would be threatened because the UK relies on a UN authority in Geneva to get access to a particular electromagnetic spectrum and moreover contractors would refuse to visit the isolated base- to service repair or deliver supplies for fear of being sued by Mauritius.

The Conservatives, Reform MPs, and some foreign diplomats challenge this argument saying the legal threat is being exaggerated and accuse ministers of being overly submissive to international lawyers and craven to politically motivated votes at the UN.

 How could the UK criticise Russia for breaking international law in Ukraine and China in the South China Sea if it was itself breaking the rules in the Indian Ocean?

UN Secretary General Antonio Guterres issued a statement welcoming the deal which said “ the value of diplomacy in addressing historical grievances”.

Under the terms of the original agreement, which was announced in October, the UK would relinguish sovereignty to Mauritius over the archipelago but maintain a 99-year lease over Diego Garcia, home to major UK-US military airbase,  finalised shortly before an election which then-Prime Minister Pravind Jugnauth lost in a landslide defeat. His successor Navin Ramgoolam has since said he had reservations about the deal, which has attracted criticism from the opposition Conservative Party in the UK and officials in the incoming Trump Administration. UK Prime Minister Sir Keir Starmer and Jugnauth called it a “seminal moment in our relationship and a demonstration of our enduring commitment to the peaceful resolution of disputes and the rule of law”. 

MPs consider whether to ratify the agreement, although the government may win the vote in view of its majority but it has yet to win the argument.