SSN-AUKUS: Opportunities, Risks and Implications

Main Image Credit On an even keel? Leaders of the AUKUS countries at Naval Base Point Lama, March 2023. Image: Associated Press / Alamy

The planned development of Australia’s own nuclear attack submarine could benefit Canberra, London and Washington – but it is not without substantial risks.

After an 18-month scoping period, the US, the UK and Australia have shed some light on the specific details of how Australia will be enabled to develop a conventionally armed nuclear attack submarine (SSN). The plan of action laid out would see Australia host four American Virginia-class SSNs and one British Astute-class on a rotational basis until the 2030s when it will purchase at least three Virginia-class SSNs. In the 2030s, both Australia and the UK will collaborate on delivering a future SSN – the SSN-AUKUS – which will share a hull structure and design with the Astute-class submarine’s successor, the SSN(R), while also incorporating a number of American technologies. As envisioned, the staged progression from hosting and then buying submarines to build institutional competencies and allow time for the development of an Australian industrial base followed by the commencement of work on a collaborative submarine design holds significant promise, but also certain challenges that will need to be mitigated.

The Short Term: A Strategically Useful but Politically Risky Proposition

One of the most significant, and perhaps slightly overlooked, consequences of the arrangement will be the basing of Virginia-class SSNs in Australia. The Australian government appears ready to both host forward-deployed American SSNs in Western Australia and to build a separate submarine base in Port Kembla on the East Coast of Australia. This has immediate strategic significance given that, currently, the American SSN fleet in the Pacific Ocean is heavily dependent on support facilities on Guam, which also hosts the US Navy’s two submarine tenders. Unsurprisingly, Guam has become a priority target for the People’s Liberation Army (PLA), which has explicitly developed capabilities such as the DF-26 intermediate-range ballistic missile with a view to targeting facilities there. The loss of facilities on Guam would substantially limit the tempo of submarine operations in the Western Pacific by forcing American SSNs to transit over longer distances to be resupplied. Moreover, given its limited geographical size and status as a single point of failure, the air and missile defence of Guam will prove challenging. The estimated cost of such a defensive system is up to $ 5 billion, and if Guam is a single point of failure in the US capacity to forward deploy and sustain submarines (among other things), the PLA could decide that devoting enough missiles to saturate the island’s defences is worthwhile.

Facilities within Australia that are capable of hosting Virginia-class submarines substantially alleviate this challenge. Australia is beyond the reach of the DF-26, and to attack it with cruise missiles launched from bombers or submarines, Chinese forces would have to run the gauntlet of the first island chain with these capabilities. That said, Australia is relatively close to likely theatres of conflict with the PLA – in particular the South China Sea – compared with the continental US. Indeed, this was a reason that it played a role as an important springboard during the Second World War.

The PLA could of course attempt to strike multiple facilities beyond the first island chain including those in Australia using strategic bombers or submarine-launched cruise missiles in the opening stages of a conflict, but this would be a more complex undertaking than saturating Guam’s defences both in terms of the number of missiles needed and the complexity of projecting power beyond the first island chain as far as Australia.

One of the most significant, and perhaps slightly overlooked, consequences of the arrangement will be the basing of Virginia-class SSNs in Australia.

There are some understandable concerns regarding the decision to sell the Virginia-class to Australia. Chiefly, concerns have been raised on whether the US workforce can build the Virginia-class at a rate of two submarines per year in addition to meeting the needs of the Columbia-class ballistic-missile submarine programme. Although the US submarine fleet will avoid falling below 50 submarines in the late 2020s by extending the life of some of its Los Angeles-class submarines, this build rate does raise concerns about meeting the navy’s target of a fleet of 66 attack submarines. However, this does not mean that the deal necessarily robs the US Navy of available submarines – the opposite could be true. A major challenge facing the American SSN fleet is maintenance backlogs at the country’s four government-owned shipyards. Currently, the US Navy has twice as many vessels awaiting maintenance as it estimates it should – 18 attack submarines out of a total of 50.  A major driver of this is the fact that the US Navy maintains 50% of the components that it needs for repairs and buys the remainder as necessity dictates. An indigenous Australian capacity to conduct repairs and refits, or even an Australian investment in a shared pool of spares as part of a promised investment in the US industrial base, could significantly improve the real (as opposed to nominal) number of submarines both countries have. Depending on how the two nations manage the question of maintenance, then, the sale of the Virginia to Australia could be a net benefit to available numbers of hulls – a point which requires both judicious investment and political communication for pushback in the US to be avoided.

The Longer Term: The Promise and Challenges of an Australian SSN

As Australia moves from buying to producing its own attack submarines, several opportunities emerge, but so do challenges. Australia expects to develop a nuclear attack submarine along the lines of the UK’s SSN(R) (the successor to the Royal Navy’s Astute-class) albeit with a number of American components with the aspiration of delivering the first boat in 2040. The key factors determining the success of the project will be design optimisation and workforce management.

First, on design, it is likely that both SSN(R) and an Australian submarine based on the same hull will carry vertical-launch cells comparable to the Virginia Payload Module. This makes eminent sense for a number of reasons, among them the fact that collaborative work on hypersonic missiles will likely be a key area of focus for Pillar 2 of AUKUS, which will focus on broader co-development of technology. Submarines, due to their size and relative stealth are a good launch platform for fast long-range missiles (which are necessarily large) and a future SSN that is equipped with a vertical-launch system (VLS) could integrate the product of collaborative efforts in the area of hypersonics. There will likely be a requirement for an increase in size to accommodate this, however, which could pose a challenge in terms of manoeuvrability in littoral waters as well as vulnerability to non-acoustic detection. There is also the question of the degree to which a hull should be optimised to operate in the littoral – where the characteristics of sound transmission impose specific design requirements – as opposed to in deeper waters such as the North Atlantic as a hunter-killer against Russian assets (a likely UK requirement). A design built for both European waters and those of the Western Pacific will be optimised for neither. We should not make too much of this design tradeoff, however – submarines such as the Astute and Virginia are already designed to operate in both littoral waters and deeper seas (albeit at the cost of optimisation). The inclusion of a VLS and necessary size increase does not automatically mean an increase in net detectability especially if a submarine such as the Virginia or the Russian Yasen-class is well equipped to avoid acoustic detection. Finally, both the UK and Australia appear to be investing in unmanned underwater capabilities such as Australia’s Ghost Shark XLUUV – and teaming them with manned assets could allow the former to be optimised for deeper waters (such as those beyond the first island chain) while the latter operate in littoral spaces. That said, decisions on how design tradeoffs should be managed should be made early – especially if a hull is to operate in both the North Atlantic as a hunter-killer against Russian submarines and in the Pacific as a littoral combatant and launch platform for cruise missiles.

As Australia moves from buying to producing its own attack submarines, several opportunities emerge, but so do challenges

The second key question that will need to be resolved is that of workforce management. Two production lines delivering the same submarine hull could, in principle, offer significant benefits to both the UK and Australia. By buying into the SSN(R) programme, Australia can support an expansion of the workforce in Barrow-in-Furness – this could still be the case even after Australia delivers its own production capacity. For example, the two could operate as part of an integrated delivery system much as General Dynamics Electrical Boat and Huntington Ingalls do in the US for the Virginia-class. In this context, the two yards build specific components and take turns at both building reactor components and final assembly of the Virginia-class. In cases where one yard owns a function (such as design, which belongs to General Dynamics) the other acts as a subcontractor. A successful division of labour between a future Australian manufacturing base and the UK’s could operate along similar lines. There are, to be sure, geographical barriers that do not exist for two US-based manufacturers but the model could work in certain respects such as design and reactor production, as well as the manufacture of specific modules which can be assembled with the hull in the commissioning country. There is, however, also a risk of the two lines drawing on the same talent pool – particularly when the Australian capability is in a nascent phase and requires external personnel to staff. Arrangements to facilitate the sharing of employees between companies might represent an avenue to mitigate this risk. For example, UK-based employees might have their employment guaranteed by domestic manufacturers but be moved on tours to Australia and vice versa. Sequencing production of Australian and British purchases and subcontracting work to ensure a steady drumbeat of orders on each production line – with demand for personnel in each production line not rising to a point where it crowds the other out of the employment market – may be an initial concern, although as Australia’s domestic workforce grows this will become less relevant.


Ultimately, the submarine deal involves both short- and longer-term opportunities to the parties involved, although it is not without risk. In the short term, it will be crucial to both shield the sale of the Virginia-class to Australia from the risk that it is seen as a diversion of capacity from the US Navy. Demonstrating both the value of diversifying basing and, potentially, Australia helping to resolve US maintenance bottlenecks could help accomplish this. In the long term, a joint effort to deliver an SSN based on the British model could allow both the Royal Navy and the Royal Australian Navy to generate much needed capacity. The project will however need to manage design tradeoffs, as well as potential early strains on human capital.

The views expressed in this Commentary are the authors’, and do not represent those of RUSI or any other institution.

Have an idea for a Commentary you’d like to write for us? Send a short pitch to and we’ll get back to you if it fits into our research interests. Full guidelines for contributors can be found here.


Dr Sidharth Kaushal

Research Fellow, Sea Power

Military Sciences

View profile


Explore our related content