Australian Deputy Prime Minister and Defence Minister Richard Marles confirmed on 31 May at the International Institute for Strategic Studies Shangri-La Dialogue in Singapore that the structure of Australia’s Virginia-class submarine acquisition under AUKUS Pillar One has changed. All three boats Australia will receive in the early 2030s will be in-service second-hand vessels, removing the new-build Block VII that was part of the original March 2023 San Diego agreement. The joint statement issued with US Defence Secretary Pete Hegseth and UK Defence Secretary John Healey described the revision as “streamlining” Australia’s acquisition, “simplifying supply chain management, operational and maintenance requirements, and maximising cost efficiencies.”

The practical logic is straightforward. Under the original 2023 plan, Australia was to receive two Block IV Virginia-class submarines currently in US Navy service and one brand-new Block VII vessel built to order. The new arrangement consolidates the entire initial fleet on a single Block IV variant. Marles framed this as good management: operating four classes of submarine simultaneously, which is what Australia would face with the full Collins extension, three Virginia variants, and the future SSN-AUKUS class, would have been operationally complex. The all-Block-IV pathway reduces that complexity to three classes and aligns the two interim Virginia boats before the SSN-AUKUS arrives in the 2040s.

Marles described the change as “definitely cost-effective” and said the option for three vintage submarines had “always been considered” as a possibility. That framing is accurate in the narrow sense that the 2023 agreement did include an option to purchase up to two additional in-service vessels if needed. The shift from option to baseline, however, is substantive. Australia is now locked into taking whatever the US Navy can release from its current active fleet rather than commissioning a new-build that would carry Australian specifications.

The revised arrangement did not emerge from nowhere. The Congressional Research Service’s January 2026 update on the Virginia-class programme stated that the actual production rate has been limited to approximately 1.1 to 1.2 boats per year since 2022, against a planned procurement rate of two boats per year. That translates to a growing backlog of submarines procured but not yet built. Newport News Shipbuilding and General Dynamics Electric Boat, the two US nuclear submarine yards, are receiving billions of dollars in congressional industrial-base funding designed to push production to two and eventually 2.33 boats per year to support both the American fleet replenishment and the Australian sale. That goal remains years away from realisation.

In that context, adding a new-build Block VII for Australia represented a scheduling commitment that the US yards could not credibly guarantee. The FY2026 budget submitted by the US Navy requested procurement of just two more Virginia-class vessels, a continuation of the reduced rate. By removing the new-build from the Australian order, Washington frees its construction schedule from a delivery obligation to Canberra while still fulfilling the alliance’s core commitment through in-service transfers. The US Navy’s 24-boat Virginia fleet provides the pool from which the three Australian submarines will be drawn.

The agreement to build SSN-AUKUS submarines in Australia in the 2040s remains unchanged, all three ministers confirmed. That programme involves a British-designed next-generation submarine incorporating Australian, American, and British technology, to be built at Osborne in South Australia by BAE Systems in partnership with ASC. Australia committed A$3.9 billion as a down payment for the new submarine construction yard in South Australia, with a further A$12 billion committed to the Henderson Defence Precinct in Western Australia.

Alongside the submarine restructuring, Hegseth and Healey announced the first signature project under AUKUS Pillar Two, the technology development pillar that covers quantum computing, undersea systems, hypersonics, artificial intelligence, and cyber capability. The project focuses on advanced payloads for uncrewed undersea vehicles. Hegseth described it as “a suite of highly adaptable multi-mission UUV payloads designed to support undersea operations and maintain our collective advantage in the maritime domain.” Healey said the systems would include sensors and weapons for undersea drones and would reach front-line forces rapidly. First deliveries are planned for 2027.

The context for the UUV programme is the accelerating threat to subsea infrastructure. Marles told the Shangri-La audience that the seabed “is becoming a battlefield” and that subsea cables have been severed at historically unprecedented rates across the Baltic and the Taiwan Strait since November 2024. He cited the fact that approximately 99 per cent of Australia’s internet traffic flows through just 15 subsea cables, making the country acutely exposed to deliberate or accidental severing of those links. The Anduril Ghost Shark programme, under a $1.7 billion Royal Australian Navy contract announced in 2025, is the platform on which a significant share of the new UUV payloads are expected to deploy.

Healey’s acknowledgment that AUKUS “talked too much and delivered too little” was candid for a ministerial joint statement. It reflects criticism that has been consistent since 2021: that the alliance has generated headlines and communiques at a rate that outpaced actual hardware in the hands of sailors. The 2027 UUV delivery date, if met, would be the first tangible near-term output of either AUKUS pillar. Virginia-class submarine transfers, even under the revised second-hand arrangement, remain scheduled for the early 2030s.

The Singapore meeting carried a diplomatic subtext. Trump’s April statement that he was “not happy with Australia” over its role in the Hormuz crisis had introduced visible friction into the alliance relationship at the precise moment Australia was making its second instalment payment to the US submarine industrial base, a payment of A$800 million confirmed in July 2025. Hegseth’s statement to SBS News in Singapore that the US is “grateful” for Australian support in the Middle East, noting that “when we’ve called Australia in this context, they’ve been willing to help,” is a clear diplomatic course correction.

Hegseth’s broader speech to the Shangri-La Dialogue maintained the Trump administration’s standard line that allies must spend more. He told the audience that the era of the United States “subsidising the defence of wealthy nations is over” and that the US wanted “partners, not protectorates.” He called out New Zealand directly, saying that its ambition to reach 2 per cent of GDP on defence was “freeloading” and “not enough.” Australia, by contrast, was on the list of regional partners Hegseth praised for increasing their spending, consistent with Canberra’s April announcement of a plan to scale defence investment from A$63.4 billion in the 2026-27 budget to A$112.1 billion within a decade.

The infrastructure commitments at HMAS Stirling on Garden Island, Western Australia, remain in place. The naval base is planned to house four US-commanded Virginia-class submarines under the Submarine Rotational Force-West project from 2027, with A$8 billion committed for associated infrastructure. Those rotational vessels are separate from the three submarines Australia will eventually own; they are American boats operating from Australian facilities as an interim measure that gives the Royal Australian Navy nuclear submarine experience years before it takes title to its own boats.

The revision changes the composition of the Pillar One submarine fleet Australia will receive in the early 2030s. It does not change the delivery timeline. It does not affect the option to purchase up to two additional Virginia-class submarines if the SSN-AUKUS programme falls behind the 2040s schedule. It does not alter the infrastructure commitments at HMAS Stirling or the Henderson Precinct. It does not change the plan to build SSN-AUKUS submarines in Australia. The sole structural change is the removal of the new-build Block VII vessel from the initial purchase, replacing it with a third Block IV in-service boat.

For the Royal Australian Navy, the practical effect is fleet homogeneity. Maintaining a single submarine variant reduces the training pipeline, the spare-parts supply chain, and the maintenance burden simultaneously. Marles was explicit about this: managing multiple Virginia variants alongside Collins and the future SSN-AUKUS class would have been “pretty complicated in terms of how you’re operating a fleet.” The all-Block-IV baseline simplifies that equation. The Australian Submarine Agency, which was established to oversee the programme, will now work toward a single interim platform type rather than managing two variants during the transition.

The cost dimension has been cited by Marles as a significant benefit, though specific savings figures were not provided in the joint statement. The original overall programme was projected by the Australian government at more than A$368 billion over 30 years, a figure cited in the 2023 announcement. A new-build Block VII submarine, procured at the current US Navy rate, carries an estimated procurement cost of approximately $5 billion per unit per the FY2026 Congressional Research Service report. Removing it from the order eliminates that procurement cost while substituting a transfer price for an in-service vessel that will be substantially lower, though the exact transfer price has not been publicly disclosed.