Guidance

Who the SDA works with

Updated 19 February 2025

The Submarine Delivery Agency (SDA) is an Executive Agency of the UK’s Ministry of Defence (MOD). We were established in 2018 to strengthen the procurement, in-service support, and disposal of UK nuclear submarines – some of the most complex programmes in the world.

We provide assured capabilities to the Royal Navy that are crucial to the delivery and maintenance of the Continuous at Sea Deterrent (CASD). To deliver our mission we work with a range of bodies and industry partners.

HMS Victorious, one of the Royal Navy's four strategic missile submarines, departs His Majesty's Naval Base, Faslane. MOD Crown Copyright.

Defence Nuclear Enterprise (DNE) 

Delivering the UK’s Nuclear Deterrent is a national endeavour and the SDA forms part of the Defence Nuclear Enterprise (DNE).  We work with a range of government organisations, most notability the Defence Nuclear Organisation (DNO), the Royal Navy, Atomic Weapons Establishment (AWE) and industry partners as ‘the Defence Nuclear Enterprise’s delivery agent for submarines’.   

The SDA, DNO, AWE and the Royal Navy form the core of the DNE, with a commitment to work as a team to help achieve common goals. Together we deliver critical projects and programmes to sustain the CASD mission. 

While the individual organisations within the DNE have unique roles and responsibilities, we share the same mission: to ‘deliver nuclear capabilities, deter the threat, protect the nation’. The SDA’s role is to contract with our industrial suppliers to ‘deliver available and capable submarines for the Royal Navy in defence of the nation’. 

Defence Equipment & Support (DE&S)

Prior to becoming an Executive Agency in 2018, the SDA was part of DE&S. Although now a separate agency, the SDA continues to work closely with DE&S on several key projects and both have their headquarters at Abbey Wood, Bristol.  There are several types of equipment that are used both on submarines and the Royal Navy’s surface ships where DE&S is the delivery agent. They therefore play a vital role in sustaining CASD. 

We have common industry partners and a coordinated approach to secure the best performance and value for money from our supply chains. 

SDA industry partners

To deliver our mission, we commission work from a broad and complex supply chain. The largest suppliers in the SDA are Babcock International, BAE Systems and Rolls-Royce Submarines Ltd.  Most of our expenditure is with or flows through these three companies, although there are more than 1,000 suppliers in the submarine supply chain. 

Babcock International

Babcock International sustains the UK’s submarine fleet, delivering through-life support to our in-service submarines and supporting critical defence infrastructure upgrades. Key activities include submarine maintenance and upgrade, as well as refitting, refuelling and decommissioning submarines. 

BAE Systems

BAE Systems Submarines is responsible for the design, build, testing and commissioning of the Royal Navy submarine’s, including the Astute and Dreadnought classes, and the future SSN-AUKUS programme. 

They also develop, support and integrate the submarine’s combat systems and equipment, which allow the submarines to operate silently and safely. 

Its main site is the shipyard in Barrow-in-Furness, with submarine-related work also conducted at sites across the UK. 

Rolls-Royce Submarines Ltd

Rolls-Royce Submarines Ltd is the UK lead in nuclear submarine propulsion systems and support services, incorporating design, procurement and operation. They design, supply and support the nuclear reactor plants that power the Royal Navy’s nuclear submarines.  

Dreadnought Alliance 

The Dreadnought Alliance was set up in 2018. It is a commercial alliance that brings together the SDA, BAES and Rolls-Royce Submarines Ltd under a joint management team. Its aim is to drive delivery performance as the Dreadnought Class submarine build programme continues.  

International Partnerships

The nature of what we do means that we work closely with other nations, and we are focussed on fulfilling our role in support of international agreements. 

AUKUS

AUKUS was announced in September 2021 and is a trilateral security partnership between Australia, the UK and the US. For all three countries, AUKUS will help meet our shared commitment to supporting stability and security through a free and open Indo-Pacific. This will be progressed by more unified defence and industrial collaboration, better information and technology sharing, and greater resilience, helping develop joint capabilities. 

AUKUS Pillar 1 will see the UK and US assist Australia to develop the capability to build and operate conventionally armed, nuclear-powered submarines (‘SSNs’). This will include Australia and the UK both building and operating a new submarine design – SSN-AUKUS – which is based on a UK design and incorporates cutting-edge US submarine technology. Construction of the UK’s submarines will take place at Barrow-in-Furness and Derby. Australia will work over the next decade to build up its submarine industrial base in South Australia. 

It was announced in March 2024 that BAE Systems will partner with ASC Pty Ltd to build Australia’s SSN-AUKUS fleet and Rolls-Royce will provide the nuclear reactors to power all SSN-AUKUS boats – both for UK and Australia. At its peak, over 21,000 people in the UK will be working on the SSN-AUKUS programme. 

Polaris Sale Agreement 

The UK works closely with the US on nuclear defence cooperation, underpinned by the 1958 Mutual Defence Agreement (renewed in 2014) and the 1963 Polaris Sales Agreement (amended in 1982 to provide for the Trident missile system).  

These agreements allow the UK to work closely with US counterparts on Nuclear Propulsion and the Trident System to improve effectiveness whilst maintaining full operational independence.