Dr Dan Boucher explains to Peers why the Diego Garcia Bill should be rejected at Third Reading, warning that its passage risks undermining international law, creating dangerous nuclear precedents in Africa and beyond, exposing the United Kingdom and its allies to long-term strategic vulnerability. He argues that a failure to resolve contradictions with the Pelindaba Treaty could weaken the rules-based international order the Government claims to uphold, and that a genuine commitment to self-determination for the Chagossian people offers a lawful and strategically sound alternative.
There are lots of reasons why Peers should vote to reject the Diego Garcia Bill on Monday. Rather than setting these all out in detail, which would require a very long article, I want to use this piece to home in on one particular imperative for a no vote.
During Committee Stage on the Bill, Lord Lilley and Baroness Goldie pointed out that the Republic of Mauritius is a signatory to the African Nuclear-Weapon-Free Zone Treaty, the Pelindaba Treaty, which commits the countries of the continent of Africa, of which Mauritius is one, to not having any nuclear weapons on their soil.
If all the Chagos Islands, including Diego Garcia, come under Mauritian sovereignty then the act of the United States or Britain bringing nuclear submarines, or indeed any nuclear weapons, to Diego Garcia would not be consistent with international law.
As Baroness Goldie explained, this difficulty needs to be seen in the context of Article 7 of the Mauritius Treaty which expressly states:
‘Each Party confirms that none of its existing international obligations or arrangements now in force or effect between it and any third party is in conflict with the provisions of this Agreement, and that nothing in this Agreement shall affect the status of existing international obligations or arrangements except as expressly provided for in this Agreement.’
And yet at no point does the treaty disapply Pelindaba from Diego Garcia, saying, as Article 7 suggests is necessary, words to the effect:
‘the Mauritius Treaty has no impact upon existing international agreements undertaken by the Republic of Mauritius other than with respect to the Pelindaba Treaty which is disapplied in relation to the island of Diego Garcia for the duration of the UK lease.’
In his response, having made much of the fact that he could not be drawn on operational matters, the Minister said he could give Peers the assurance that:
‘…the Government of Mauritius, the Government of the UK and the Government of the US see no contradiction in what the treaty says, and explicitly lay out, in respect of the ability of Diego Garcia to operate in the way that it has always done, with the lethal capabilities as outlined elsewhere in the Bill.’
The only sense that could be made of this was that the three countries have decided they will not worry about any contradiction between what the Pelindaba Treaty says and the absence of any provision releasing Mauritius from the treaty, as required by Article 7, in respect of Diego Garcia.
The clear consequence of this was helpfully alluded to by Lord Lilley in his response to the Minister:
‘I am not persuaded that that is necessarily in line with the Pelindaba Treaty. That does not worry me so much. It may worry the noble and learned Lord, Lord Hermer, or any future Lord Hermer in Mauritius, but let us hope that they will be ignored.’
In this context it is not surprising that Lord Lilley then tabled a Report Stage amendment to revisit the difficulty this week. His amendment stated that the main provisions of the Act, including the transfer of sovereignty, must only come into force ‘when the Secretary of State has sought to negotiate guarantees from the Government of Mauritius that Mauritius will not enforce its duties under the Pelindaba Treaty on the base at Diego Garcia and if they were to do so the sovereignty of the base would revert to the UK.’
Meanwhile, Lord Morrow approached matters from the different vantage point of seeking a commitment from the Minister that, in the context of Article 7 of the treaty not disapplying Pelindaba in relation to Diego Garcia, both the Government of the UK and the Government of the United States were solemnly pledging that from the transfer of sovereignty they would not take nuclear submarines or nuclear weapons to Diego Garcia. No doubt recalling the Government’s somewhat mysterious and veiled response during Committee Stage, Lord Morrow concluded his questions at Report saying:
‘But I very gently say that while of course he must not discuss operational matters, this cannot be pushed as an excuse for dodging questions about compliance with international law. Any attempt to deploy that stratagem, to the point of avoiding the demonstration of compliance with international law when non-compliance is feared, would form a deeply troubling precedent.’
The Minister’s response, however, failed to address the presenting questions from either perspective and stated that there will be no diminishment in the operational freedoms in use of the base, and that the United States and our ‘five eyes partners’ all approved the deal, so no one should worry. To Lord Morrow, specifically, he said:
‘Similarly, with respect to the noble Lord, Lord Morrow, …he is keen to understand the impact of the treaty on the rules-based international order. Again, all I can say is that the treaty has been welcomed by our international partners, including the UN Secretary-General, the Commonwealth Secretary-General and the African Union.’
The first difficulty arising from the Minister’s failure to directly address the questions put relates to the fact that this does not sit at all well with the priority the Government accords to complying with international law which has been central to the justification for the Mauritius Treaty and Diego Garcia Bill. Their approach has been based on the contention that, notwithstanding the controversy surrounding the treaty and the merely advisory standing of the 2019 judgment of the International Court, that the rules based international order is of such supreme importance that we must comply even with its non-binding judgements. In this the entire rationale for the Mauritius Treaty and the Bill was a highly developed respect for the rules-based international order.
And yet the implication of the approach of the Government is that either: a) it is saying that both the UK and the USA are solemnly undertaking that after the proposed transfer of sovereignty neither country will ever take nuclear submarines or nuclear weapons to Diego Garcia without saying so (which seems impossible given their statement that there will be no narrowing of the operational scope of the base), or b) they are saying, or are at least vulnerable to being perceived as saying, it is acceptable for the Republic of Mauritius to break international law in relation to Pelindaba just with respect to Diego Garcia.
If it is the latter then the imperative for the Mauritius Treaty, and Diego Garcia Bill is at once negated because the threat to the rules based international order arising from the UK not complying with a non-binding judgement is trifling in comparison with the UK and USA, two permanent members of the UN Security Council, encouraging, or being perceived as encouraging, Mauritius to violate a binding international treaty. To make matters worse this treaty is very consequential, pertaining to the use of nuclear weapons on or from the continent of Africa. This would create a precedent that could be appealed to by countries from South Africa to Egypt, from Morocco to Zimbabwe, to not fully comply with Pelindaba. It affords them the opportunity to state that, while they remain fully committed to the vital Pelindaba treaty in relation to 99% of their territory, for reasons of national security, they will have to assume some flexibility with respect to the remaining 1%. That would involve the appropriation of the Mauritius Treaty not for the purpose of upholding the rules based international order but for its subversion.
In the second instance, we have to ask whether the UK Government has unpacked the implications arising from the previous approach of the Republic of Mauritius to the UK Government in its discussion with the US and our ‘five eyes partners’. The advisory judgement makes it clear that Mauritius sided with the UK on the creation of BIOT in 1965 in return for £70 million in today’s money. And yet this has not stopped Mauritius from subsequently performing a spectacular U-turn, working with other countries in the international community against the UK to argue that what London had sought was, in fact, a violation of international law.
The presenting risk is compounded on this occasion because it provides an opportunity to hostile foreign powers. They now have the option of trying to constrain the operational freedom of the base by pressing Mauritius to increasingly question the US and UK about their use of Diego Garcia because of the Mauritian liability under the Pelindaba Treaty as the sovereign authority. At some point they could even encourage Mauritius to suggest to the wider international community that it has felt some pressure by these two permanent members of the UN Security Council to not fully apply Pelindaba to Diego Garcia and seek to turn the rest of the international community against the US and UK. A hostile power would no doubt reassure Mauritius that if any of this placed the UK-Diego Garcia lease income stream in jeopardy, they would ensure that Port Louis would not lose out.
As if that was not enough, a document just seen by the Conservative Post, and attributed to a Chinese whistleblower, suggests that Beijing is closely monitoring potential strategic opportunities arising from a proposed transfer of sovereignty over the Chagos Archipelago from the United Kingdom to Mauritius, with particular attention to the US-UK military base on Diego Garcia.
The text states that the sovereignty transfer could create a “window of opportunity” in which existing agreements underpinning Western access to Diego Garcia become more vulnerable. Among other things, the document focuses on opportunities arising from the fact that Mauritius is as a signatory to the Pelindaba Treaty.
If the Diego Garcia Bill is passed on Monday, and the requisite secondary legislation is passed in the weeks following, then the treaty can be ratified and sovereignty transferred. In this there is every chance of history repeating itself. Mauritius could appeal to the wider international community and argue that in the same way the UK wrongly persuaded it to agree to the detachment of the Chagos Islands in 1965, in violation of international law, it has now persuaded them that it is OK for Diego Garcia to be under Mauritian sovereignty and yet for the islands to host nuclear weapons, notwithstanding their Pelindaba obligations.
In this instance it is not hard to imagine what much of the international community would have to say. Mauritius and China would have international law on their side. If the UK said, you can’t do this, then Mauritius would cite its obligation both under the Pelindaba Treaty, and under Article 7 of the Mauritius Treaty, to uphold the Pelindaba Treaty, and the only option would be for the UK and US to yield to the requirements of the Pelindaba treaty in relation to Diego Garcia or seek to assert control over the Chagos Islands by force.
The truth is that arrangements set out in this Bill, and the Mauritius treaty, leave the United Kingdom, and the United States, wide open to manipulation from Mauritius (and who knows what complexion of government it might have over the next 99 years) and powers like China.
The critical point to bear in mind in all this is that the difficulty could be entirely avoided if the UK and US Governments responded positively to the self-determination petition of the Chagossian Government in Exile and its First Minister, Misley Madarin. If they provide the Chagossian people self-determination, with the options of either becoming part of Mauritius or becoming a resettled British Overseas Territory, the polling is clear that the Chagossians would vote for the latter. In this context the islands would remain legitimately under British sovereignty and the need to lease Diego Garcia would not exist, the problem with the Pelindaba treaty would not exist and the wider problems arising from setting precedents about the appropriateness of only loosely applying nuclear arms treaties would not exist. The Diego Garcia US military base could remain in place, with complete operational freedom, and the historic injustice against the Chagossians would be put right. In this self-determination is the solution to what otherwise threatens to be an impending Indo-Pacific geo-strategic crisis, the very thing the US National Security Strategy says the United States Government is anxious to avoid.
Faced with the prospect of the Mauritius Treaty being implicated in both (at least) the perception of the UK Government encouraging a country to not fully abide by international law in relation to nuclear weapons (together with the associated message this sends to other countries), and the probability of growing operational constraints on Diego Garcia that are likely to encourage some to attempt resolution through the use of force, there is now an urgent imperative for Peers to reject the Diego Garcia Bill at Third Reading on Monday. This would prevent the ratification of the treaty and its coming into force which can only happen if the Bill becomes law. Even if the Government then applied the Parliament Act, this would provide 13 precious months in which to make the case for the win-win solution which is full self-determination and the resettlement of the Chagos Islands as a British Overseas Territory hosting the Diego Garcia base. Instead of violating international law this move would uphold it and in a way that enabled the Diego Garcia military base to operate with complete freedom, and without forming dangerous precedents that could be used by African countries to be less than rigorous in complying with their Pelindaba commitments.
In voting ‘no’ the Lords would fulfil its constitutional duty as a check on the Commons and do so with complete freedom because rather than being a manifesto commitment the Diego Garcia Bill actually violates the 2024 Labour manifesto which pledges to ‘always defend their [British Overseas Territories] sovereignty and right to self-determination’.
By Dr Dan Boucher
Dr Boucher has a PHD in sovereignty and international relations.
