Mauritius has sent a ship to the disputed Chagos Islands, which it claims for itself, although the islands are adminstered by the UK, which has a joint military installation there in partnership with the US.
The UK administered Mauritius and the Chagos Islands as a single colonial unit until their separation in 1965. While Mauritius claims that there were strong political, social, and cultural links, the UK disputes such associations, asserting that the links were irrelevant, with only loose administration of the Chagos islands from Mauritius during that period.
At the time, the UK purchased territory in its entirety from Mauritius, intending to close the plantations on the island and form a joint military installation with the United States. The UK attempted to deport the locals to the Seychelles and Mauritius, but Mauritius actually refused the deportees without a condition of cash transfers from the UK.
The Mauritian government is now using those same deportees, now identifying as Chagossians, by sending them to the Chagos Islands in its attempt to press claims over its sovereignty over them, claims denied by the UK, which has stated:
The UK has no doubt as to our sovereignty over the British Indian Ocean Territory, which we have held continuously since 1814. Mauritius has never held sovereignty over the territory and the UK does not recognise its claim. However, the United Kingdom has a long-standing commitment, first made in 1965, to cede sovereignty of BIOT to Mauritius when it is no longer required for defence purposes. We stand by that commitment, which has been found to be legally binding. Thus no recent assessment has been made of other options for ceding the territory.
Thus, the UK has expressed its willingness to cede the territory, but given no timeline as to when that will take place.
Current UK administration of the islands previously proved a thorn in the side of Mauritius when it tried to press claims of its sovereignty to claim the EEZ in the seas surrounding the Chagos Islands, a claim which was eventually recognized under the the International Law of the Seas, at the expense of the Seychelles.