UK sends one of its few operational attack submarines HMS Anson to Australia under AUKUS agreement.

The UK has sent the HMS Anson, an Astute-class nuclear-powered attack submarine, to Australia as part of the AUKUS agreement, allocating one of its few Royal Navy operational attack submarines to the Indo-Pacific during a period of constrained fleet availability.

As reported by Navy Lookout on January 19, 2026, the British Royal Navy has started the deployment of the HMS Anson, one of its few operational nuclear-powered attack submarines, to Australia as part of the AUKUS Submarine Rotational Force–West framework. The Astute-class submarine departed Faslane on January 10, 2026, beginning a long-distance deployment in the Indo-Pacific via Gibraltar, while drastically reducing the number of UK attack submarines available for operations in the North Atlantic and European waters.
Follow Army Recognition on Google News at this link

The Royal Navy has few attack submarines actively at sea because all are tied up in maintenance or trials, leaving other allied navies filling gaps in undersea protection for deployed surface groups. (Picture source: UK MoD)

The HMS Anson departed Faslane on January 10 and reached Gibraltar as her first port of call, marking the opening stage of a transit of roughly 9,500 nautical miles toward Western Australia. In December 2025, Defence Minister Luke Pollard stated that this deployment of an Astute-class submarine was a core planning assumption for the Royal Navy under AUKUS and assessed as manageable within existing force planning. Its timing has nonetheless attracted attention because it coincides with a period of sharply reduced British submarine availability, as the decision directly allocates one of the few operational attack submarines to a distant theater for an extended period.

The HMS Anson (S123) is the fifth Astute-class nuclear-powered submarine operated by the Royal Navy, representing the newest generation of British conventionally armed attack submarines. She was ordered in March 2010, laid down in October 2011, launched in April 2021, and commissioned in August 2022, with sea trials completed in May 2024. The submarine is powered by a Rolls-Royce PWR2 reactor that does not require refueling during its service life, allowing effectively unlimited range constrained by crew endurance and supplies. She displaces more than 7,000 tonnes submerged, measures 97 meters in length, and operates with a core crew of about 98 personnel. Her armament includes six 533 mm torpedo tubes capable of deploying Spearfish heavyweight torpedoes and Tomahawk Block IV cruise missiles, enabling anti-submarine warfare, maritime strike, and land-attack missions.

However, fleet readiness assessments have estimated that only two out of the theoretical ten submarines in the Royal Navy’s nuclear-powered fleet were able to go to sea immediately at one stage, with only one of the six Astute-class attack submarines formally in commission at higher readiness and four others assessed as being at low or very low readiness due to maintenance and refit cycles. The HMS Astute is awaiting access to dry dock for a mid-life refit once another submarine completes maintenance. The HMS Ambush is reported to be at very low readiness and has been partially stripped of components to support other boats. The HMS Agamemnon, although commissioned in September, remains many months from operational availability.

In the case of the HMS Audacious, it completed a historic 363-day deployment in April 2023 but then remained alongside in Devonport dry dock for over 16 months due to limited availability of refit space and resources necessary to complete maintenance on schedule. As a result, the assignment of HMS Anson to Australia has a direct impact on the UK attack submarine fleet availability. On the other hand, from Australia’s perspective, the deployment of the HMS Anson will support operations from HMAS Stirling as part of the AUKUS Submarine Rotational Force–West. The purpose is to host British and U.S. nuclear-powered attack submarines on a rotational basis rather than as permanently based units.

This arrangement allows Australian naval personnel to gain practical exposure to nuclear-powered submarine operations, maintenance routines, and support requirements before Australia fields its own nuclear submarines. It also provides Australia with an allied undersea presence in the Indo-Pacific during the transition period before future Australian submarines enter service. For the United Kingdom, operating from Western Australia also restore a regular submarine operating experience in the Indo-Pacific, a region where British attack submarines have not been continuously deployed for many years.

Still, the scale of the deployment imposes practical constraints on how long the HMS Anson is likely to remain in Australia. U.S. submarines rotating through the same framework are expected to operate on cycles of about six months. For a Royal Navy submarine, the transit distance of roughly 9,500 nautical miles each way makes short rotations less efficient. Longer forward stays reduce the proportion of time consumed by transit and increase the operational return from the deployment. The duration of HMS Anson’s stay has not been publicly specified, leaving open questions about how long the submarine will be unavailable for European tasking. Gibraltar’s role as an early stop, including visible crew rotation, highlights that the deployment is not only a strategic choice but also a logistical and manpower calculation for the UK.

At the same time, the deployment takes place against a backdrop of heightened concern about maritime security closer to the United Kingdom. Russian naval activity has been increasing, particularly in the North Atlantic, where attack submarines play a central role in surveillance and deterrence. The First Sea Lord stated in December 2025 that the long-standing advantage enjoyed by allied forces in the Atlantic is at risk, adding that the margin is now narrow. With frigate numbers at very low levels and broader maritime initiatives still in development, attack submarines represent a critical element of the United Kingdom’s conventional deterrent posture. The absence of available British submarines has been partially offset by U.S. Navy activity, but this does not replace national capability. Each long-distance deployment, therefore, reduces flexibility in responding to nearer-term contingencies.

The strategic trade-off is particularly visible when only one or two submarines may be operational at a given time, which is the case today. Efforts have been launched to improve the UK's submarine availability through accelerated maintenance initiatives, including a 100-day program initiated in September 2025 to address systemic delays. While these efforts aim to return submarines to service more quickly, concrete outcomes that significantly change the immediate availability picture have not been confirmed. The third Astute-class submarine, the HMS Artful, is identified as a potential near-term addition to the operational fleet, which could provide at least one submarine for European operations, but no public return-to-sea date has been announced.

The overall submarine readiness challenge is also driven by limited dockyard capacity, extended maintenance periods, and interdependencies between refit schedules. These constraints mean that commissioning dates do not translate directly into deployable capability. In this environment, each submarine’s status has disproportionate operational and strategic weight. Therefore, the dispatch of HMS Anson to Australia might illustrate the balance the Royal Navy is attempting to strike between long-term political commitments and near-term operational constraints. Participation in AUKUS and the Submarine Rotational Force–West is a fixed obligation that supports cooperation and future capability development with both the U.S. and Australia.

But, at the same time, the reduced number of available submarines exposes the United Kingdom to gaps in coverage in the North Atlantic and surrounding waters. The benefits of an extended Indo-Pacific deployment coexist with increased risk in nearer theaters during the same period. The situation underscores the impact of historic underinvestment in support infrastructure on current operational output. Whether the balance eases will depend on the return to service of other Astute-class submarines in the coming months. Until then, HMS Anson’s deployment remains a clear example of how limited submarine availability shapes the UK's strategic choices.

Written by Jérôme Brahy

Jérôme Brahy is a defense analyst and documentalist at Army Recognition. He specializes in naval modernization, aviation, drones, armored vehicles, and artillery, with a focus on strategic developments in the United States, China, Ukraine, Russia, Türkiye, and Belgium. His analyses go beyond the facts, providing context, identifying key actors, and explaining why defense news matters on a global scale.