HMAS Stirling and Submarine Rotational Force-West

How a naval base near Perth is being prepared to host rotating US and UK nuclear-powered submarines, and why it matters for Australia's own fleet.

Explainer · Updated 26 October 2026

HMAS Stirling is a Royal Australian Navy base on Garden Island, near Perth in Western Australia [1][10]. Under AUKUS it has a central role. It is where US and UK nuclear-powered submarines will rotate from 2027, and where Australia's own nuclear-powered submarines will later be supported [1][3].

That rotational presence is called Submarine Rotational Force-West, or SRF-West. This page explains what it is, why it exists and what is being built.

What SRF-West is

The plan announced in March 2023 is for the UK and US to establish a rotational presence at HMAS Stirling of one UK Astute-class submarine and up to four US Virginia-class submarines, from as early as 2027 [1]. The Australian Submarine Agency (ASA) and Defence describe the same numbers [2][3].

In May 2026, the three defence ministers confirmed that key milestones for SRF-West were being met and announced that the arrangements needed to establish it in 2027 had been finalised [4]. They said the US had authorised US Navy support elements for SRF-West and would begin rotating the first US Navy personnel to HMAS Stirling later in 2026 [4].

Why it exists

SRF-West is a training and readiness step. The ASA says it will help Australia be able to own, operate, maintain and regulate a fleet of nuclear-powered submarines from the early 2030s [2]. The Government has described the rotations as key to "our ability to be sovereign ready" [9].

The 2023 plan also had Australian sailors joining US crews for training and development during submarine visits [1]. Maintenance is the other main strand, covered below.

The May 2026 ministerial statement added that SRF-West will support submarine deployments by expanding maintenance options and support infrastructure in the region [4].

Not a foreign base

The 2023 White House fact sheet said the rotational presence "will comply fully with Australia's longstanding position of no foreign bases on its territory" [1].

The ASA says the submarines will not be permanently based in Australia, and that the US elements will be carried out under the US-Australia Force Posture Agreement [2]. The Australia-UK Geelong Treaty of July 2025 includes support for the rotational presence of a UK Astute-class submarine at Stirling [7].

Maintenance work already done

Maintenance is a large part of SRF-West. The ASA said the most complex maintenance on a US nuclear-powered submarine in Australia to that point was planned at HMAS Stirling in the second half of 2024 [5].

The UK has also taken part. The May 2026 ministerial statement noted "the successful Submarine Maintenance Period conducted earlier this year by HMS ANSON" [4].

Looking ahead, the ASA says Australia is expected to provide about 1,800 days of cumulative maintenance in partnership with the US Navy, from the start of SRF-West until the first Virginia-class submarine is transferred to Australia in the early 2030s [6].

Upgrading the base

The 2023 plan said HMAS Stirling would be expanded to support nuclear-powered submarines, both visiting and rotational boats and Australia's own future fleet [1]. The ASA says the base will be upgraded over the next decade, with Defence responsible for delivering the infrastructure [10].

Key facts from Defence's project page [3]:

The SRF-West Priority Works were referred to Parliament's Public Works Committee on 6 June 2024. Community information sessions were held in Rockingham in July 2024, a public hearing followed on 2 August 2024, and an expediency motion was passed on 22 August 2024.
Early construction works began in 2024, after Parliamentary approval in late 2023.
Main construction works began in August 2025, after environmental approval.
The SRF-West Priority Works project was approved under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC 2024/10031).
Defence Housing Australia has signed three contracts with Western Australian businesses for 550 additional households for Defence personnel and families over the next five years.

On cost, a parliamentary committee reported an $8 billion commitment to prepare Stirling for SRF-West and Australia's own submarines [8]. In May 2026, defence ministers described Australia's planned investments of "up to AUD 8 billion" at SRF-West for infrastructure and logistics support at HMAS Stirling [4]. Our budget explainer puts this in context.

Western Australia's wider role

The Prime Minister's March 2023 release expected about $1 billion of investment in Western Australia over four years [9]. Nearby, the Henderson Defence Precinct has a separate AUD 12 billion commitment, which ministers said includes support for contingency docking and maintenance capabilities [4]. A parliamentary committee said Henderson's primary purpose is continuous naval shipbuilding and that it will also contribute to AUKUS [8].

Key terms

SRF-West. Submarine Rotational Force-West, the rotational presence of UK and US nuclear-powered submarines at HMAS Stirling [2].
Astute class. The UK's current class of nuclear-powered attack submarine. One will rotate through Stirling [1].
Virginia class. The US Navy's nuclear-powered attack submarine. Up to four will rotate through Stirling, and Australia plans to buy three [1].
Sovereign ready. The Government's term for Australia being ready to own and run its own nuclear-powered submarines [9].

Where SRF-West fits

SRF-West is the first major phase of the Optimal Pathway. It comes before Australia buys its Virginia-class submarines in the early 2030s and before the first SSN-AUKUS boats are built in Adelaide.

Frequently asked questions

Where is HMAS Stirling?

On Garden Island, near Perth in Western Australia [1][10].

How many submarines will rotate through Stirling?

One UK Astute-class submarine and up to four US Virginia-class submarines, from as early as 2027 [1][2].

Is SRF-West a US base?

No. The ASA says the submarines will rotate through HMAS Stirling and will not be permanently based in Australia, consistent with Australia's position of no foreign bases on its territory [1][2].

Sources

Checked 26 Oct 2026. AUKUS Defense is an independent site, not affiliated with any government. Plans and figures may change; check the sources above for the latest.