Written questions by Francois.

With reference to Article 9(1) of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), how he will exercise (a) prescriptive and (b) adjudicative jurisdiction over Diego Garcia as defined in Article 19 of the Agreement to ensure operational continuity.

The prescriptive enforcement and adjudicative jurisdiction afforded to the United Kingdom under the agreement enables the UK to write, enforce, and adjudicate laws applicable on Diego Garcia. The detail of His Majesty’s Government's approach will be set out in implementing legislation.

With reference to the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what steps his Department is taking to ensure the storage of (a) fuel and (b) weapons in Diego Garcia as defined in Article 19 of the Agreement (i) comply with the environmental laws of the Government of Mauritius and (ii) maintain operational readiness.

The United Kingdom is not bound by Mauritian environmental law. Under Article 5, the UK will apply applicable international environmental law with due regard to applicable Mauritian environmental laws; this reflects the long-standing Defence policy of applying both our own and our host nations' environmental standards so far as it is reasonably practicable. Annex 1.2.ii explicitly puts the management of fuels, weapons and other hazardous materials under UK control.

What estimate he has made of the cost of the public purse of contributing to the Government of Mauritius’s maritime security including (a) training and (b) equipment over the next ten years.

As set out in the new UK-Mauritius Strategic Partnership Framework, Mauritius and the United Kingdom will cooperate on matters relating to maritime security. Further engagement on the details of this cooperation with Mauritius is ongoing. Our contribution will focus on providing training and building institutional partnerships which will contribute to preserving the safety, security, stability and prosperity of the Indian Ocean region and will support the future operation of the Base on Diego Garcia.

With reference to paragraph 3(h) of Article 2 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what steps he plans to take to ensure the Government of Mauritius's regulation of the provision of electronic communications services does not impact the communication systems of Naval Support Facility Diego Garcia.

The UK has unrestricted ability to control and manage the electromagnetic spectrum for Diego Garcia and the surrounding 12 nautical miles. Decisions related to the electromagnetic spectrum beyond Diego Garcia will be taken jointly by the UK and Mauritius at the Joint Commission, which is described in Annex 3 of the Treaty. There can be no decisions without UK agreement.

With reference to Article 5(3) of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what steps his Department is planning to take to co-operate with the Government of Mauritius on (a) illegal, (b) unreported, and (c) unregulated fishing in the Chagos Archipelago.

In conjunction with the steps taken elsewhere in Government, the Ministry of Defence will support closer collaboration between the UK and Mauritius in this area by providing training which boosts Mauritian maritime security capabilities and maritime domain awareness.

With reference to paragraph 1(a) of Annex 1 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), whether the Agreement permits (a) access, (b) basing, and (c) overflight rights for (i) United Kingdom and (ii) United States forces in the (i) territory, (ii) waters and (iii) airspace of the Government of Mauritius outside of Diego Garcia as defined in Article 19 of the Agreement.

In respect of the Chagos Archipelago beyond Diego Garcia, vessels and aircraft of the United Kingdom and the United States of America shall have unrestricted rights of overflight, navigation and undersea access.

With reference to paragraph 8(b) of Annex 2 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what steps his Department plans to take to provide assistance to the Government of Mauritius for the carrying out of all necessary investigations into offences; and what estimate has he made of the cost to the public purse of such assistance over the next ten years.

As per paragraph 10 of Annex 2, the UK and Mauritius will be agreeing separate arrangements and operating procedures as necessary to assist and facilitate the exercise of Mauritian jurisdiction in respect to paragraph 8. There will be no additional facilities on island to enable Mauritian jurisdiction.

What assessment he has made of the risk of the Government of Mauritius inviting non-allied security forces to operate in the Chagos Archipelago.

Under the treaty, no third-party security force can operate without the consent of the UK.

With reference to paragraph 3(f) of Annex 1 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what mechanism will be put in place to ensure any joint decision with the Government of Mauritius on the (a) construction and (b) emplacement of any (i) maritime installation, (ii) sensor, (iii) structure and (iv) artificial island does affect Naval Support Facility Diego Garcia operations.

A Joint Commission will oversee implementation of the treaty and will discuss issues relating to the effective operation of the base on Diego Garcia. No joint decision can be taken in the Joint Commission without UK agreement. Additionally, under the Treaty Mauritius commits not to undermine, prejudice or otherwise interfere with the long-term, secure and effective operation of the base.

With reference to paragraph 3(e) of Annex 1 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what steps his Department is planning to ensure the departure of any security force from the Chagos Archipelago whose continued presence is not agreed under paragraph 3(d).

The Treaty clearly states a strict prohibition on foreign security forces operating in the Chagos Archipelago without UK consent. If a security force is operating in the Chagos Archipelago without the joint agreement of the UK and Mauritius, we will cooperate as necessary, to prevent or otherwise bring to an end such activity.

With reference to Article 6 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what steps he will take to ensure the resettlement programme does not impact the security of operations at Naval Support Facility Diego Garcia.

Under the treaty, Mauritius will have the ability to conduct resettlement on any island in the Chagos Archipelago other than Diego Garcia. The UK has no intention of constraining resettlement activity, but has negotiated an effective veto over any activity that presents a clear and direct threat to the base on Diego Garcia.

With reference to Article 2(3)(g) of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what steps his Department is taking to ensure that military operations in Diego Garcia as defined in Article 19 of the Agreement are not impeded by compliance with the environmental laws of the Government of Mauritius.

The United Kingdom is not bound by Mauritian environmental law. Under Article 5, the UK will apply applicable international environmental law with due regard to applicable Mauritian environmental laws; this reflects the long-standing Defence policy of applying both our own and our host nations’ environmental standards so far as it is reasonably practicable.

Whether the costs for the UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia [CS Mauritius No.1/2025] are accounted for under his Department's Resource Departmental Expenditure Limit; and what estimate he has made of the potential impact of these costs on (a) his Department's operational budget and (b) the Government’s commitment to increase defence spending to 2.5% of GDP by April 2027.

These are being considered as part of the wider Government engagement on the second phase of the Spending Review, which concludes on 11 June 2025.

What the terms of reference are for the investigation into unauthorised social media posts by a British Army regiment.

The Army has investigated a number of social media posts which were published in error and without correct authorisation. Those posts have been removed and updated guidance has been issued to Regimental HQs on the appropriate use of regimental websites and social media pages. This work has been conducted as part of Army routine business, with no additional costs incurred.

Who is leading the investigation into unauthorised social media use by a British Army regiment.

The Army has investigated a number of social media posts which were published in error and without correct authorisation. Those posts have been removed and updated guidance has been issued to Regimental HQs on the appropriate use of regimental websites and social media pages. This work has been conducted as part of Army routine business, with no additional costs incurred.

What his planned timeline is for concluding the investigation into unauthorised social media use by a British Army regiment; and whether he plans to make a Statement to Parliament on the findings of the investigation.

The Army has investigated a number of social media posts which were published in error and without correct authorisation. Those posts have been removed and updated guidance has been issued to Regimental HQs on the appropriate use of regimental websites and social media pages. This work has been conducted as part of Army routine business, with no additional costs incurred.

Whether the findings of the investigation into unauthorised social media use by a British Army regiment will be made publicly available.

The Army has investigated a number of social media posts which were published in error and without correct authorisation. Those posts have been removed and updated guidance has been issued to Regimental HQs on the appropriate use of regimental websites and social media pages. This work has been conducted as part of Army routine business, with no additional costs incurred.

What estimate he has made of the cost of the investigation into unauthorised social media use by a British Army regiment.

The Army has investigated a number of social media posts which were published in error and without correct authorisation. Those posts have been removed and updated guidance has been issued to Regimental HQs on the appropriate use of regimental websites and social media pages. This work has been conducted as part of Army routine business, with no additional costs incurred.

What the cost is of the L129A1 Sharpshooter Rifle programme for the Royal Marines; and whether additional costs have been incurred due to the adoption of the 6.5mm Creedmoor calibre.

The L129A1 is provided to the Royal Marines from the Army, via Defence Equipment and Support, as part of the Lead Command Model. The total cost to Defence was £1.5 million. Additional costs have been incurred for Creedmoor as the transition to this calibre has not commenced yet.

What budget has been allocated to Project Eve; what the (a) current and (b) anticipated future spend are for that project; and what steps he is taking to ensure interoperability with the (i) Army’s and (ii) Royal Navy’s communications systems.

As part of the Commando Force (CF) Programme, £99.78 million has been spent on spiral development and fielding of the EVE digital backbone capability. A further £56 million budget for EVE is approved as future spend, to enable interoperable development and scaling to Littoral Strike Group level by December 2030. EVE, developed by the Royal Navy, has been a pathfinder in Defence digital innovation. EVE has been fielded by the Army’s Very High Readiness forces, as part of the Land Environment Tactical Communications and Information Systems programme. EVE is an integral part of the wider Royal Navy Strike Network design.