What is the Chagos deal that Trump has approved?

According to No 10, Donald Trump has "signed off" on the highly controversial Chagos Islands deal, drawing to a close the tortuous process of securing the future of the UK-US military base that has been operating on Diego Garcia since 1965.

- SEAN O'GRADY

It means formal sovereignty of the British Indian Ocean Territory (BIOT) will be ceded to Mauritius, and comes as something of a shock to opponents who fully expected Mr Trump to reject the change. The long saga may be coming to a close...

What’s the deal?

Some of the basics are still unknown, especially as regards money, but the position will be that the BIOT – comprising the Chagos Islands and the military base – will be transferred to Mauritian sovereignty. In return, the UK has been promised a 99-year lease on the islands, with military use by the US part of the deal, in return for an annual fee. The fee has not yet been disclosed but is thought to be some £90m per annum, inflationlinked.

But aren’t the islands British anyway – why give them away?

The small matter of international law. Successive appeals by Mauritius to the UN and the International Court of Justice have left the status of the BIOT in doubt, generally favouring the Mauritian position.