Jack speaks with Richard Ekins, professor of law and constitutional government at Oxford University, about the United Kingdom’s plan to transfer sovereignty over the Chagos Islands to Mauritius while leasing back the Diego Garcia naval base for continued U.S.–U.K. military use—an issue that has drawn renewed attention in recent weeks after President Trump publicly criticized the proposed agreement. They discuss the historical background of the Chagos Islands dispute, the role of international courts, treaty obligations between the United States and the United Kingdom, and the strategic importance of Diego Garcia. They also examine the legal and security risks of the proposed transfer, including constraints on the use of force, nuclear nonproliferation obligations, and the question of why the United States might consent to the agreement.
Since this chat was recorded, President Trump today signaled support for the Chagos sovereignty transfer, or at least a rollback of his criticism. He also said: “If the lease deal, sometime in the future, ever falls apart, or anyone threatens or endangers US operations and forces at our Base, I retain the right to Militarily secure and reinforce the American presence in Diego Garcia.”
Mentioned:
“Britain’s Chagos Deal Can’t Go Forward Without U.S. Consent” by Richard Ekin (National Review, Jan. 30, 2026.)
Thumbnail: Diego Garcia photographed by the Sentinel 2 satellite in 2021. (European Space Agency / CNES).
This is an edited transcript of an episode of “Executive Functions Chat.” You can listen to the full conversation by following or subscribing to the show on Substack, Apple, Spotify, or wherever you get your podcasts.
Jack Goldsmith: Today’s chat is about Great Britain’s plan to hand control of the Chagos Islands in the Indian Ocean to the Republic of Mauritius. This event may seem irrelevant to executive functions, but it is quite relevant for two reasons. The Chagos Islands are home to the vitally important U.S.–U.K. military base, Diego Garcia.
And until yesterday, anyway—and the news reports are still unclear on this—President Trump has been a strident critic of the impending deal. To help sort this out, I’m going to chat with Professor Richard Ekins, who is a professor of law and constitutional government at Oxford, a distinguished global professor of law at Notre Dame, and head of the Judicial Power Project at Policy Exchange, a leading U.K. think tank. Professor Ekins is an expert on this matter, and he’s been very critical, in publications both in the United Kingdom and the United States, of the British government’s plan to return sovereignty over the islands to Mauritius.
Richard, good morning. Can you explain, for listeners who don’t know much—if anything—about this, the background to this episode?
Richard Ekins: Sure. So, the Chagos Islands are an archipelago of about 60 islands in the Indian Ocean, 300 miles south of the Maldives, 1,300 miles northeast of Mauritius. As you say, the Diego Garcia base is located therein.
Diego Garcia is far and away the biggest island in the archipelago and exceedingly well located, sometimes referred to as the Malta of the Indian Ocean—a single aircraft carrier, as your term is familiar, I’m sure. So, a very, very significant base. The Chagos Islands became part of the British Empire in 1814, as part of the Treaty of Paris.
They were, before that, French, and ceded to the U.K., to Britain, in 1814, along with Mauritius and the Seychelles. And in 1965, the Chagos Islands were excised from the colonial territory of Mauritius. They were nominally administered as part of the colony of Mauritius, despite being a very long way away and having no meaningful connection other than that sort of accident of colonial boundaries.
So, they were excised from the colony of Mauritius, renamed the British Indian Ocean Territory, and preparations were made for a U.S.–U.K. military facility. The Mauritian government was compensated for this. This was in advance of independence.
Mauritius became independent in 1968. The people who lived on the Chagos Islands, the Chagossians, were removed from the islands, and the base was built. In 1982, Mauritius initiated a claim to the Chagos Islands, having otherwise said, well, they’re British.
Mauritius played quite an effective hand through the international institutions across the subsequent decades. I think it did a very effective job of leveraging the injustice done to the Chagossians, who were removed in a pretty high-handed fashion, without adequate compensation being paid.
In 2017, Mauritius persuaded the General Assembly to refer the question of the Chagos Islands to the International Court of Justice for an advisory opinion. That was over the head of the U.K. and the U.S., who said this was an inappropriate matter for an advisory opinion—there’s a live dispute between Mauritius and the U.K.
In 2019, the International Court of Justice issued an advisory opinion saying the decolonization process in the Chagos Islands had been incomplete. The U.K. government said, well, it’s an advisory opinion; we’re not going to do anything about it, thank you very much.
In 2021, a special chamber of the International Tribunal for the Law of the Sea, in a dispute between the Maldives and Mauritius, took for granted that the 2019 advisory opinion had established that Mauritius was sovereign.
In 2022, the then Conservative government of the U.K. entered into negotiations with Mauritius about the future of the Chagos Islands. I published my first paper for Policy Exchange on this matter in 2023, saying it was a very bad idea to hand the islands over.
The then government didn’t. But in October 2024, shortly after they came into office, the new Labour government of the U.K. reached an agreement with Mauritius to transfer sovereignty and lease back Diego Garcia for 99 years, with substantial annual payments to be made each year for continued use of the base—or the island for the base, I should say.
The agreement has yet to be ratified. It was officially signed in May 2025, but the parliamentary process for ratification hasn’t been completed, and it’s not clear, obviously, whether the U.S. administration supports it or not. That’s where we’re at.
Okay, great. So, I want to talk about legal issues first, and then we can talk about policy issues, and they may blend together. So, there’s a 1966 treaty between the United Kingdom and the United States that says the territory shall remain under United Kingdom sovereignty—referring to the Chagos, I believe, or Diego Garcia?
No, referring to the whole Chagos Islands, and actually an island chain off to the west of the Indian Ocean, too. That was handed over to the Seychelles when they became independent in 1976.
Okay, and you’ve argued—and I think the U.K. government has acknowledged—that United States consent under that treaty, the 1966 treaty, is a prerequisite to the transfer of sovereignty to Mauritius. So, did I get that right, and can you explain that?
Exactly. I mean, this came sort of to light in some public discussion only a few weeks ago, when President Trump came out and denounced the agreement on the 20th of January. I think the U.K. government had understandably thought American consent was in the bag, but it was made clear—by me and by others—that we have a treaty commitment, the U.K. to the U.S., that the Chagos Islands will remain under U.K. sovereignty. And unless that’s changed, if we go ahead and transfer sovereignty to Mauritius, we’ll be in breach of the 1966 treaty.
So, that treaty has to change—that agreement has to change—before ratification can go ahead, at least can go ahead without the U.K. immediately being in breach of the treaty with the U.S., and being in breach of its treaty with Mauritius, because we agree in that treaty that we’re not breaching any other obligations when we hand the islands over.
So a couple of questions here. First of all, I guess we should first talk about what is the U.S. position as of Thursday morning? I mean, President Trump several weeks ago said this was a stupid idea; the impending transfer represented, “total weakness,” and was great stupidity.
It seemed then that he was going to veto this or wasn’t going to give consent. In the last 36 to 48 hours, I’ve read news reports in Great Britain—but less certain in the U.S. news reports—that President Trump is indeed going to consent. There’s been some agreement reached.
Can you tell us where things stand as of Thursday?
Well, it is unclear, as you say. So, there were news reports last night in the U.K. that, surprisingly, in a way, President Trump was going to sign off, and that Number 10 was awaiting a phone call from President Trump to sign off, so to speak—which was a surprise.
And the news reports suggest that somehow Prime Minister Starmer had persuaded him that all was well. It’s a suggestion that further security assurances were going to be given by the U.K. to the U.S. Quite unclear what that means. Quite unclear, actually, how the U.K. would be in a position to give further assurances, unless that means reopening the treaty with Mauritius—but there’s been no suggestion of that yet.
So, we have to wait and see if it’s true, in fact, if that is President Trump’s position, and if he is, in fact, going to let this go forward.
Okay. Let’s talk about what’s been in the background—the security assurances. Just explain why Diego Garcia is so important and what the concerns are from a military, national security, defense perspective. Just list the concerns as you see them from transferring sovereignty from Great Britain to Mauritius.
Well, so it’s an exceedingly significant air and naval base because of its location—very good for projecting power into all sorts of utterly critical locations. I think that’s acknowledged by—
Flesh that out, I mean, a little bit.
Oh, so, well, I’m not a military expert, but I think given the—
The standard understanding of the importance of Diego Garcia.
Sure. So, it was used throughout the Iraq wars. It’s a base that is within striking range of the Persian Gulf and the Straits of Malacca. And if you’re looking at the map, it’s sort of right in an utterly critical position for, sort of, dominating the Indian Ocean—maybe not dominating, but projecting power from.
So, there are very good reasons why the U.K. has wanted to retain control for defense purposes, and why the U.S. has viewed it as very significant too. And I think there are a host of important U.S. Navy facilities there, and Air Force, and so on.
So, it’s, I think, very widely acknowledged to be extremely significant. The question is, in the U.K. government’s argument for, sort of, handing the islands over to Mauritius is: yes, it’s a very significant base; they’re not attempting to diminish it. It’s because of its significance that we have to reach an agreement with Mauritius. That’s their argument—or at least their headline argument. There’s another argument going on beneath, I think.
I don’t buy the argument, because I think exchanging U.K. sovereignty, subject to Mauritian challenge, for Mauritian sovereignty, subject to the terms of the treaty, is a bad trade. I think it’s a bad trade for a host of reasons—but to begin with—the term of the lease agreement is 99 years. There is an option of renewal, but the option is not practically enforceable, I think, and one could certainly foresee it not being capable of being actually exercised.
And it’s perfectly foreseeable that in 99 years this will remain an utterly critical strategic asset, which would be foolish to yield—not to be able to continue to exercise, or worse, to be taken up by a hostile state, the obvious one being China, but who knows what things are like in 100 years.
So, I think it’s short-sighted. But even within the 99-year period, I think exchanging U.K. sovereignty—again, subject to Mauritian challenge—for Mauritian sovereignty introduces dangers that are not otherwise there.
And the dangers being that, yes, the U.K. and the U.S., according to the terms of the treaty, will remain in sort of exclusive control of Diego Garcia, and there are some related legal risks we’ll probably come to, but they’ll stay there on the island.
But there are a lot of other islands in the archipelago, and their use—or their misuse—would be a security risk for Diego Garcia. Now, the terms of the treaty provide for the exclusion of foreign military forces from there, but there are options open, including Chinese fishing vessels, or nominal scientific installations, or so on and so forth, where, if projects go ahead there—which the U.K., as it stands, could simply deny and evict—things could go ahead that pose a threat to the base.
So, what are the—two questions, actually. One: what is the reason beneath the stated reason why the British government is doing this?
Yeah, so I said the reason beneath. I think there’s a mix of two. So, one is post-colonial guilt, which is related to—it’s maybe part and parcel of the same thing—but the Chagossians, as I said, were badly treated in the late ’60s, early ’70s.
Now, they’ve been compensated, and in a sense more recently compensated. Very many of them are now British citizens, but there’s, I think, understandably, a kind of guilty conscience about what went on. And Mauritius has done a very good job at leveraging that injustice and that guilty conscience into a “you can remedy it by transferring sovereignty to us.”
That’s certainly the view of many international human rights lawyers and similar. Now, I think it’s nonsense in a way. I think actually going ahead with this treaty will compound the injustice rather than address it, because Mauritius has a very poor record for how it deals with the Chagossians. Most Chagossian groups are opposed to the treaty.
So, it’s a misleading ground for action, but I think it’s part of what’s in the mix.
The other ground, which maybe is even more interesting, is I think there’s a certain vision of international law that’s driving the present government. The present government was led—Keir Starmer was a distinguished human rights lawyer; his attorney general was a leading human rights lawyer as well.
They have a certain understanding of international law, human rights, that I think drives their approach to governing. And this was a decision made, you know, to hand the Chagos Islands over—a decision made early on in their government, before, frankly, things started to go wrong and they had to think more prosaically about the project of governing.
And it’s an early speech given by our attorney general where he refers to the succession of the Chagos Islands to Mauritius as, “this showcases our sort of total commitment to the rule of law.” Now, again, I think this is nonsense.
I don’t think international law requires the U.K. to hand the islands over. I think, in fact, we’re surrendering to the abuse of international adjudication—effectively letting an International Court of Justice advisory opinion function like a binding adjudication—when the U.K. didn’t consent to adjudication, doesn’t have to consent to adjudication, and yet is being—having that sovereign right subverted.
But I think that that’s definitely part of what’s going on. And you can partly tell that not least by public statements, but also what the Labour Party was saying when they were in opposition, where there were many appeals to the international rule of law as just making it obvious we have to hand the islands over.
Okay, I want to come back to that vision of international law in a moment, but let’s move to, I think, what you’re referring to when you talk about legal risk for the United States. So, explain what potential restrictions there are under the transfer of sovereignty treaty between Great Britain and Mauritius—what possible restrictions there could be on the United States’ use of the base.
I’m thinking about—and it’s actually a different treaty; you can explain this to us—the possible storing and usage of nuclear weapons from there, and the use of force generally. Can you explain what the legal regimes are that might impact that?
Sure. So, I mean, the terms of the treaty: the Chagos Islands, including Diego Garcia, become sovereign Mauritian territory, but the U.K. will have effectively exclusive control over Diego Garcia. So, it will be a U.K.-based—well, U.K. facility—which is jointly operated with the United States.
And the U.K. will undertake various commitments to Mauritius in relation to this, one of which is that all operations that take place out of Diego Garcia will be compliant with international law, which obviously includes prohibitions on the use of force.
And U.K. consent is required before Diego Garcia is used for U.S. operations. That’s the case now; it’s the case after this treaty goes ahead. And so, the U.K. really will be undertaking to Mauritius that it won’t let the U.S. use the base as a base for military operations unless it’s compliant with international law prohibitions on the use of force.
So, it’s perfectly foreseeable if, say, the agreement were in place now and President Trump decided to tamper with his reaction against Iran in support of the protesters—serious argument, of course; not saying compelling, but serious argument—that that would not be compliant with international law, and that would place pressure on the U.K. to deny use of the base to the United States for that purpose.
And now, those arguments would loom large with the U.K. in any case, but Mauritius would have standing to insist that we were in breach of the agreement if it took the view that the actions that were going on there were non-compliant.
So, I think you’re adding in not just, you know, what does the U.K. think about the use of force? The U.K. may take a different view to Mauritius, especially if Mauritius comes under pressure—as is entirely foreseeable, I think, in the medium term.
But—and what about the Treaty of—is it Pelindaba?
Pelindaba, yeah—nuclear-weapon-free zone. So, Mauritius, along with a lot of other African states, has undertaken to prohibit the stationing of nuclear weapons on its territory. If this treaty goes ahead, Diego Garcia will be Mauritian territory, and the Treaty of Pelindaba will apply.
And so, Mauritius will be required, as a matter of that treaty, to prohibit the stationing of nuclear weapons on Diego Garcia. Now, the U.K. government seems to have either persuaded itself, or will think, there’s some way around this—that this just won’t be a problem.
And I don’t really know what they were thinking, other than maybe Mauritius just won’t be that interested; it’ll look away, which doesn’t seem a sustainable strategy—especially given that any signatory to the treaty can raise this as a concern, and there can be forced inspections to determine if nuclear weapons are being stationed.
There are arguments about what “stationing” means, but it seems there’s a pretty serious risk that the U.K. and the U.S. would be placing Mauritius in breach of the treaty.
And then, of course, Mauritius could say, well, you can’t place us in breach, and thus you’re in breach of the agreement, and we’re entitled to countermeasures—we can let the Chinese set up a base on the other islands without being in breach of the treaty ourselves, et cetera. It’s quite hard to know how this would exactly unfold.
It looks like there’s a pretty serious legal risk to me there.
So, this leads to the thing I really don’t understand about all of this. I understand the current U.K. government’s vision of international law, I understand that perspective. I understand the guilt argument clearly. I can understand why the U.K. might want to transfer sovereignty here.
What I don’t understand at all is why the U.S. is even thinking about giving consent. That vision of international law is the antithesis of the vision of international law that the Trump administration holds.
Given—just to go sideways a little bit—given the rhetoric and reality of what they’re trying to do in Greenland, and the importance that they place on control of strategically important landmasses for national security, and given the Trump administration’s vision of international law, and given the risks—whatever the risks actually are—we’re talking about international law, legal entanglements, and the politics related to those, and how that might influence decision-making in Washington.
But all of these things are things that the Trump administration is not remotely interested in, doesn’t care about. So, I’m having a very hard time understanding, in light of all that, why the Trump administration is even considering consent to this.
Is there a good answer to that?
Well, I share your bemusement as part of the answer. I mean, when Trump was elected, I think the British government were deeply worried that he would veto the agreement for sure. They put considerable effort into persuading him and the administration that it was the right thing to do.
My impression—and it might be, you know, it’s not based on anything inside—is that Trump was willing to go along with it, maybe sentimental attachment to Britain, or maybe Keir Starmer is somehow awfully persuasive when he’s one-on-one with the president. I don’t know.
He was willing to go along with it without looking too closely at the detail, perhaps. Surprising, because I think, like you, that he places a premium on control, and it’s pretty surprising to think that a—what really is a campaign of lawfare, or harassment by legal means, and it is abusive international law, I think, rather than international law as it probably is conceived—it’s strange to think you’d be complicit in the surrender to that.
Now, it looks, two weeks ago, as though President Trump had, in a sense, turned his mind back to this and was not liking what he saw. Maybe that’s still the case today—unclear.
But it certainly does seem surprising to prefer Mauritian sovereignty, when Mauritius is clearly going to be a target of Chinese subversion. I think it is a risk to U.K. sovereignty.
So then—this is my last question. It’s still a puzzle to me. It sounds like it’s a bit of a puzzle to you, too, about the U.S. position.
What possible security guarantees could the British have given the Americans? This is what’s being reported in the news—that…
Yeah, I find this very mysterious.
Just, is there anything that they could have said or done that actually would give the U.S. assurance on these questions, or is that—
Well, I mean, we’re just going off the reporting, of course. So, maybe the assurances—I mean, this wouldn’t be giving new assurances, would it? It would just be trying to explain why you think what you’ve already agreed is good enough, which, for the reasons we’ve been through, I don’t find persuasive.
I don’t see how the U.K. is in a position to give any further assurances unless it reopens the treaty with Mauritius and somehow reaches new terms. And if they do that, they could come up with a more watertight deal. But that’s going back to the beginning again, and there’s been no suggestion of that.
So, I don’t think the U.K. is in a position to offer further security assurances. And, you know, the kind of fundamental position—you hand over sovereignty; Mauritius will be sovereign, and it will have capacity to decide what happens in important respects. I mean, it’s not going to forcibly evict the U.S. Navy from Diego Garcia, obviously. But it can make life awfully difficult, and it can do so under a color of legal right, because it will be sovereign.
As it stands, it can try and make life difficult, which is what the British government fears, but it can only do so by abusing international institutions and by directly threatening U.S.–U.K. defense interests.
At that point, if Mauritius starts to threaten those defense interests, you should think, well, maybe you can take some measures in response. So, it’s a very strange sort of chain of reasoning.
All right. Well, we’ll see what happens. That was all very elucidating, Richard. Thank you very much.
You’re very welcome.
