Diego Garcia Military Base and British Indian Ocean Territory Bill

Lord Coaker Excerpts

Tuesday 25th November 2025 Lords Chamber

[Baroness Goldie (Con)]

My Lords, my Amendment 88 in this group is very much in a similar vein to my earlier amendments, although I see I do not have the presence of my newly acquired fan—the noble Lord, Lord Kerr of Kinlochard—to encourage me. I seek reassurance that the

“unrestricted access, basing and overflight”

provisions in Annex 1(1)(a) of the agreement includes the right of the UK to allow nuclear-propelled vessels and nuclear-armed vessels and aircraft to enter the sea and airspace of Diego Garcia.

Although not in the amendment, the annexe of the treaty referred to also specifically covers the United States of America, and, for the avoidance of doubt, I include it in the confirmation I seek from the Secretary of State in this amendment. Again, I am asking that this be confirmed by the Secretary of State before the Bill can come into force. In this respect, I am perhaps baring my teeth more than my noble friend Lord Lilley, which is a rather unusual situation.

As my noble friend Lord Lilley pointed out, Mauritius is a party to the Pelindaba treaty, which establishes the African continent as a nuclear-weapon-free zone. This prohibits the research, development, manufacture, stockpiling, acquisition, testing, possession, control or stationing of nuclear weapons in any signatory state. Article 7 of the Mauritius treaty states that both Mauritius and the United Kingdom confirm that no

“existing international obligations or arrangements … 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”.

Annex 1 of the treaty states that the United Kingdom retains

“unrestricted ability to … control the … deployment of armed operations and lethal capabilities”.

Nuclear weapons are lethal capabilities. So Britain and the United States must, as per the terms of the treaty, have an unrestricted ability, surely, to house nuclear weapons or to dock nuclear submarines at the base on Diego Garcia should we choose to do so. Yet that would appear to require an express provision in this treaty, and I cannot find it.

Article 7(3) appears to seek to allay those concerns, but I would welcome an absolute clarification from the Minister. Will Mauritius’s membership of the Pelindaba treaty prevent us basing Vanguard-class submarines or, in the future, nuclear-armed aircraft, or the United States stationing any nuclear weapons at the base on Diego Garcia? That is a question that I require answered. This cannot be left in doubt—hence my requirement that the Secretary of State publish a statement to confirm the matters I have raised before this Bill comes into force, so that everyone is clear about what the UK and the US can or, perhaps more alarmingly, cannot do. As my noble friend Lord Lilley commented, although they are not directly covered by the Pelindaba treaty, my amendment also makes reference to nuclear-propelled vessels and, for the avoidance of doubt, I seek reassurance that Mauritius would not take exception to that. I look forward to the Minister’s response.

[The Minister of State, Ministry of Defence (Lord Coaker) (Lab)]

My Lords, I thank the noble Lord, Lord Lilley, and the noble Baroness, Lady Goldie, for their amendments. I appreciate that they have questions about how the treaty protects the full operation of the base, and I want to reassure them that the treaty enables the continued operation of the base to its full capability. The treaty and the Bill we are debating today will have zero impact on the day-to-day business on Diego Garcia. Importantly, it will not reduce our ability to deploy the full range of advanced military capabilities to Diego Garcia. I am putting some of this on the record, and the noble Baroness, as a former Defence Minister, will know the careful calibration of the language that I am using: I am putting it on the record so that we are all clear.

As I say, noble Lords will understand that I pick my words with care in this particular context. I cannot and will not discuss operational matters on the Floor of this place, but I am confident that the Chamber would not necessarily want me to. The long-standing UK position of neither confirming nor denying the location or presence of nuclear weapons must stand. But let us talk about the hypothetical. The amendments from the noble Lord, Lord Lilley, and the noble Baroness, Lady Goldie, concern the application of the Pelindaba treaty. Mauritius is a signatory, as the noble Lord, Lord Lilley, and the noble Baroness said, to the treaty. The UK is not a signatory to the treaty but is a signatory to Protocols 1 and 2. I can confirm to the Chamber that the Governments of the UK and Mauritius are both satisfied that the Diego Garcia treaty is compatible with these existing obligations.

I also remind colleagues, because this is important—again, I think the noble Lord, Lord Lilley, if I remember rightly from his remarks, and, indeed, the noble Baroness raised this—that we are not alone in the matter. The Government of the United States have also tested all aspects of the Diego Garcia treaty in depth and at the highest levels of the security establishment. They, too, are satisfied that it protects the full operation of the base. Indeed, when I was talking about the earlier amendments in answer to that, I quoted the remarks of Secretary of State Marco Rubio and his comments about being satisfied with the treaty in every aspect.

Amendments 63 and 88 therefore are not necessary. We do not need a review of the impacts of nuclear treaties on the future operation of the base, as the noble Lord, Lord Lilley, has proposed, because the future operation of the base has been protected. I say to the noble Baroness that we do not need to reopen paragraph 1.a of Annex 1 to the treaty, as has been suggested, because this already provides for unrestricted—that is the key word—access for UK and US vessels to enter the sea of Diego Garcia. Paragraph 1.b.i provides for unrestricted ability to control the conduct and deployment of lethal capabilities.

[Baroness Goldie (Con)]

I am grateful to the Minister for giving way. I do of course understand the sensitivity of not discussing operational activity in a public domain. However, if I revert to the Minister’s understandable reliance on what I described at Second Reading as that “huge protection” in Article 1, that is explicitly in contradiction with Article 7(1). Article 7(1) says expressly with reference to international obligations or arrangements that, if they are not to be obtempered or agreed to, that must be provided for in this agreement. That is the dilemma that is perplexing my noble friend Lord Lilley and myself. We seem to have on the face of this treaty a self-evident contradiction.

[Lord Coaker (Lab)]

I understand the point that the noble Baroness is making. What I am saying to her is 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 lays 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.

I hope that is helpful to the noble Lord, Lord Lilley, and the noble Baroness as reassurance that the situation will stay the same as it is now. As I have said, all those three parties to that treaty are confident that that remains the case.

I will say, however, that, although resisting the amendments, I am grateful that they were tabled. They are really important amendments to have made in order for the Government to have put on the record important elements of the treaty and the Bill. We have been able to clarify for the Chamber, and for those who read our proceedings, that the position that we would all want to see will continue with respect to Diego Garcia and that the full capabilities will be maintained.

Let me be absolutely clear: the full operational use of the base is protected to ensure that the base is able to continue in every way that it always has done. I hope that is helpful. On the basis of the reassurances that I have made and the comments that I have put on the record, I hope that the noble Lord, Lord Lilley, will feel able to withdraw his amendment.

[Lord Lilley (Con)]

That is very helpful and I entirely respect what the Minister says. He is a man of obvious integrity and commitment to the defence of this country. I am comforted that he is speaking for the Government, and therefore that the Government will maintain the freedom to use the Diego Garcia base to its full capabilities. 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. So I will, of course, withdraw my amendment.