Britain signed a multi-billion dollar deal on the future of the Chagos Islands with Mauritius after a last-gasp injunction was overturned, securing itself a lease for the U.S.-UK Diego Garcia air base for the next century.

The British government’s plans to hand control of the strategically significant Chagos Islands to Mauritius are set to be signed off on Thursday, after an 11th-hour legal injunction failed to stop an effort that has been intensely controversial in both the United Kingdom and the United States.

Mauritius and Russia have agreed to strengthen ties, amid fears that the UK was too hasty in deciding to hand over the Chagos Islands.