Testing AUKUS: America’s uncertainty, Britain’s bet, and Europe’s choices

An extended US review has cast uncertainty over the future of AUKUS, unsettling the partnership just as the United Kingdom and Australia formalize their commitments through the Geelong Treaty.

Key takeaways:

AUKUS, a trilateral security partnership formed by Australia, the United Kingdom, and the United States in 2021, is facing its first significant test. In June 2025, the US Department of Defense initiated a review that raised doubts about Washington’s willingness and capacity to deliver Virginia-class submarines to Australia, reviving long-standing concerns about American reliability. Although negotiations on a long-term framework for SSN-AUKUS, a planned class of nuclear-powered attack submarine, were already underway, the Geelong Treaty, signed by the UK and Australia in July 2025, assumed heightened significance in this context. Presented as a binding fifty-year pact between the two countries, the treaty was widely seen as an attempt to anchor the program and hedge against US unpredictability. These developments underscore the competing dynamics within AUKUS: a deepening of UK-Australia collaboration set against persistent uncertainty in Washington, a fluid situation that presents both lessons and opportunities for Europe.

When first announced in 2021, AUKUS was presented as a bold experiment in minilateral defence cooperation. Its two pillars—the acquisition of nuclear-powered submarines (Pillar I) and cooperation on advanced technologies (Pillar II)—were intended to enhance deterrence and promote closer industrial integration in the Indo-Pacific. While Pillar I centred on Australia’s acquisition of a new capability, it also bound both the United Kingdom and Australia to the future SSN-AUKUS design. From the outset, the arrangement carried both “promise and peril”: it was ambitious but costly, controversial, and politically contingent. By 2023, the Pillar I submarine roadmap, unveiled at San Diego’s Point Loma naval base, projected steady progress. Two years later, however, cracks are already visible in Washington’s wavering commitment, even as Australia and the United Kingdom move to reinforce the pact.

The US review: “America First”

In June 2025, the US Department of Defense announced a review of AUKUS that focused primarily on the submarine pathway. The review will be led by Elbridge Colby, Under Secretary of Defense for Policy and a vocal skeptic of AUKUS, who frames US security strategy in “America First” terms. Officially, the review is intended to assess the sustainability of existing commitments; in practice, it signals Washington’s ambivalence about the agreement.

Two factors triggered the process. The first was industrial. US shipyards currently produce only 1.1–1.3 Virginia-class submarines per year, well below the 2.3 required to meet both domestic and Australian needs. The second was political. Donald Trump’s return to office in January 2025 has led to renewed insistence that US resources should not be diverted abroad at the expense of America’s own fleet. Whereas periodic alliance reviews typically emphasize solidarity and reassurance, this exercise has been framed narrowly in terms of capacity and national priorities. For America’s AUKUS partners, it appears less a routine review than a test of whether the arrangement can withstand the swings of American politics.

Originally scheduled for completion within 30 days, the review has been repeatedly extended and is now expected to conclude by the end of 2025. The delay has intensified uncertainty in Canberra and London. Mixed signals from US officials—with some reaffirming commitment and others hinting at retrenchment—have further unsettled AUKUS partners. Australia, in particular, has invested heavily in sustaining the pact. In July 2025, Canberra made an A$800 million (€486 million) payment to expand US shipyard capacity, bringing its total contribution to A$1.6 billion (€899 million). That Australia is underwriting US industrial infrastructure even as Washington reviews whether it will deliver submarines underscores the asymmetry of dependence within the partnership.

Australian leaders have sought to downplay the risks. Prime Minister Anthony Albanese has presented the review as a matter of routine alliance management rather than a crisis, reassuring domestic audiences that the pact remains robust while signalling to Washington that Canberra is a reliable partner willing to shoulder burdens. Yet this framing belies growing anxiety that, without the timely delivery of Virginia-class submarines, Australia faces a serious capability gap. The Collins-class boats, which were expected to be retired in the late 2020s, now require an expensive life-extension program to remain operational through the 2030s and into the 2040s. Even with this stopgap, a shortfall looms well before SSN-AUKUS submarines are delivered.

For the United Kingdom, the review is equally unsettling. It undermines confidence in Washington’s strategic commitments and highlights the vulnerability of AUKUS to the domestic oscillations of US politics.

The Geelong Treaty: A hedge against US unpredictability

Negotiations on a long-term framework for SSN-AUKUS cooperation, announced at the AUKUS defence ministerial meeting in September 2024, culminated in the signing of the Geelong Treaty by the United Kingdom and Australia on 26 July 2025. The treaty is a legally binding fifty-year defence agreement covering the design, construction, operation, sustainment, and disposal of SSN-AUKUS submarines. It marks a significant formalization of an already ambitious pathway, transforming political intent into binding obligations over the course of half a century.

Unlike AUKUS itself, which remains a political partnership without treaty status, the Geelong Treaty creates legally enforceable commitments. It binds Australia to British expertise, technology, and industrial capacity, embedding the United Kingdom in Indo-Pacific security for generations. For Canberra, it secures access to British know-how, accelerates skills transfer, and offers greater certainty that the project will advance even if Washington falters. Politically, Prime Minister Albanese can point to the treaty as evidence that Australia is not solely dependent on an unpredictable United States.

For the United Kingdom, Geelong turns its “Indo-Pacific tilt” into a durable presence. It ensures work for British shipyards, reinforces London’s claim to global strategic relevance after Brexit, and ties Australia’s submarine future to British reactors and propulsion systems. At a time of fiscal strain and competing responsibilities in Europe, the agreement provides London with a long-term stake in the Indo-Pacific security landscape.

Yet this long-term commitment carries risks. Binding Australia to British industrial capacity for fifty years reduces flexibility. If costs escalate, schedules slip, or political will in London wanes, Canberra will have limited alternatives. The treaty effectively ties Australia’s most ambitious defence project to the economic health of the UK. Moreover, it does little to address the looming capability gap of the 2030s: Collins-class extensions can delay this inevitability but not eliminate it. The Geelong Treaty offers reassurance for the 2040s and beyond but leaves near-term uncertainties unresolved.

Although presented as a means to secure the submarine program’s industrial and operational framework, the treaty functions in practice as a hedge, giving Canberra and London greater certainty should US politics or priorities shift. The absence of an equivalent treaty with Washington underscores an uncomfortable reality: of the three partners, the United States appears the least reliable. As a result, AUKUS risks drifting from a trilateral arrangement toward a dual-track partnership, binding Australia and the United Kingdom more tightly together while the United States remains the least committed of the three.

What does it mean for Europe?

The turbulence surrounding AUKUS holds lessons, challenges, and opportunities for Europe. From the outset, European policymakers were skeptical of the initiative. France regarded the loss of its submarine contract with Australia as a betrayal, while EU leaders criticized the lack of consultation and the exclusion of European partners from Indo-Pacific security planning. The current US review has revived these concerns, underscoring that questions of legitimacy and reliability remain unresolved.

That such a major defence agreement is being reassessed only four years after its announcement highlights the volatility of American commitments. This strengthens the case in Brussels, Paris, and Berlin for greater strategic autonomy, lending fresh momentum to calls for a stronger European defence industrial base and enhanced capacity to act independently.

The industrial dimension is equally instructive. America’s shipbuilding bottlenecks reveal the risks partners incur when they tie their defence futures to US production cycles. For Europe, the issue is less about the absence of capacity (its naval industries remain substantial) than about the need to invest more broadly in indigenous capabilities across critical domains such as cyber, artificial intelligence, and quantum technologies. Strengthening resilience would reduce dependency, enabling Europe to shape defense innovation on its own terms, rather than being constrained by Washington’s priorities.

There is also a geopolitical opening. With AUKUS under strain, Europe has an opportunity to expand its role in Australia’s security relationships. Germany and Italy could pursue technological and industrial collaboration, while Australia and the EU have already begun negotiating a Security and Defence Partnership that encompasses defence industry, cybersecurity, counterterrorism, and critical technologies. If Europe can translate the concept of strategic autonomy into tangible partnerships, it can bolster its Indo-Pacific profile on its own terms and demonstrate that it is capable not only of normative power projection but also of delivering practical security contributions alongside key Indo-Pacific partners.

Conclusion

AUKUS now finds itself in a period of pronounced uncertainty. The ongoing US review has unsettled the submarine pathway and raised doubts about the extent of Washington’s commitment, even in the absence of a final decision. Australia and the United Kingdom, by contrast, have moved in the opposite direction: the Geelong Treaty binds them together for fifty years, transforming political intent into a legal obligation.

The result is an uneven partnership, with two members doubling down while the third pauses to reassess. Until Washington clarifies its position, the future of AUKUS will depend less on industrial planning than on American domestic politics. Canberra and London can deepen their collaboration, but the initiative cannot achieve its intended weight without US follow-through.

The reverberations are also felt in Europe. The episode highlights the vulnerability of partners to shifting US commitments, sharpening the case for greater strategic autonomy. At the same time, it creates openings for deeper ties with Australia: ongoing negotiations on a Security and Defence Partnership offer Europe the chance to shape its own role in the Indo-Pacific. Whether current uncertainty resolves into renewed cohesion or persists as instability will influence not only Australia’s defence posture and Britain’s global role, but also Europe’s choices about autonomy and partnership in a volatile Indo-Pacific.

Funding acknowledgment: This work has received funding from the European Union’s Horizon Europe coordination and support action 101079069 — EUVIP — HORIZON-WIDERA-2021-ACCESS-03. Funded by the European Union. Views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Executive Agency (REA). Neither the European Union nor the granting authority can be held responsible for them.