The UN's International Court of Justice (ICJ) said on Monday the UK was "under obligation" to relinquish its control of the Chagos Archipelago after finding that authorities acted unlawfully in separating the islands from Mauritius during decolonisation.
In the advisory ruling, the ICJ urged the UK to complete decolonisation "as rapidly as possible."
"The United Kingdom is under an obligation to bring an end to its administration of the Chagos Archipelago as rapidly as possible, thereby enabling Mauritius to complete the decolonisation of its territory in a manner consistent with the right of peoples to self-determination," it said.
Mauritius gained independence from Britain in 1968, but not before separating three years earlier with the Chagos Islands, which are known to the UK as the British Indian Ocean Territory.
This controversially led to the displacement of thousands of islanders to make way for a US military base on the archipelago's largest island, Diego Garcia.
Following Monday's advisory opinion, Chagos Support UK, a support group for Chagossians resettled in the UK, remained focused.
The "verdict is certainly a win for Mauritius, but it remains to be seen whether or not this is a win for the Chagossian people," the group said on Twitter.
"The question of sovereignty has no bearing on the right of return or for the imperative for both the UK and Mauritius to treat Chagossians with the rights and respect that they deserve. That includes proper compensation and access to British citizenship."
"All must acknowledge the right to self determination of the Chagos Islanders and any decisions about the future of the Chagos Islands must be made by those who once inhabitated them and their descendants."
The UK Foreign Office said: “This is an advisory opinion, not a judgment," in a statement sent to Euronews.
"Of course, we will look at the detail of it carefully. The defence facilities on the British Indian Ocean Territory help to protect people here in Britain and around the world from terrorist threats, organised crime and piracy."
'We are so happy'
However, outside the courthouse in The Hague, the atmoshere was a little more upbeat.
Louis Olivier Bancoult, the head of the Chagos Refguees Group, told reporters he was "so happy" following the advisory verdict.
When asked if he thought he would be able to go home, Bancoult said: "of course, of course!"
"It could not be possible that other people can live on our land..." he said.
Mauritian Prime Minister Pravind Jugnauth told Reuters the non-binding verdict was a "historic moment" for Chagossians.
“Our territorial integrity will now be made complete, and when that occurs, the Chagossians and their descendants will finally be able to return home," he said.