Washington said the deal protected the long-term, secure and effective operation of the strategic military base.

After years of negotiations, the UK is giving up its sovereignty over a cluster of strategically important Indian Ocean islands. The move has led to criticism from Britain's Conservative opposition and some local Indigenous groups.

For years, Mauritius demanded the UK end its control on the Chagos Archipelago. Why was their ownership a matter of contention, and what are the interests of countries like the US and India here? We explain.