The Geelong Treaty: The UK and Australia Move Forward with AUKUS

08/15/2025
By The Defense.info Analysis Team

On July 26, 2025, Australia and the United Kingdom formalized their commitment to the AUKUS submarine program by signing the Geelong Treaty, a landmark 50-year bilateral defense agreement that represents one of the most significant developments in Anglo-Australian military cooperation since World War II.

This treaty, formally known as the Nuclear-Powered Submarine Partnership and Collaboration Treaty, establishes the framework for unprecedented cooperation in developing next-generation nuclear-powered submarines while reinforcing the broader AUKUS alliance’s strategic objectives in the Indo-Pacific region.

The Genesis of the Geelong Treaty

The Geelong Treaty emerges from the broader AUKUS partnership announced in September 2021, which brought together Australia, the United Kingdom, and the United States in a trilateral security arrangement designed to counter growing challenges in the Indo-Pacific.¹

The treaty’s signing represents the materialization of commitments made in the AUKUS Naval Nuclear Propulsion Agreement, which was signed by all three nations in August 2024 and enabled the transfer of sensitive nuclear propulsion technology to Australia.²

The treaty was signed during the Australia-UK Ministerial Consultations (AUKMIN) in Geelong by UK Defence Secretary John Healey and Australian Defence Minister Richard Marles, with UK Foreign Secretary David Lammy and Australian Foreign Minister Penny Wong also participating in the broader diplomatic discussions.³

Strategic Significance for Australia

For Australia, the Geelong Treaty represents a fundamental shift in its naval capabilities and strategic posture. The agreement enables Australia to develop its first nuclear-powered submarine fleet, marking the nation’s entry into an exclusive club of countries operating such advanced naval assets. The treaty facilitates comprehensive cooperation on the design, build, operation, sustainment, and eventual disposal of the SSN-AUKUS submarines, ensuring that Australia will have full lifecycle management capabilities for its future fleet.⁴

The submarine program addresses Australia’s unique geographic challenges, with nuclear-powered vessels offering the range and endurance necessary to patrol the vast distances of the Indo-Pacific effectively. Unlike conventional diesel-electric submarines, nuclear-powered boats can remain submerged for months and travel at high speeds over intercontinental distances, dramatically enhancing Australia’s ability to project power and maintain sea lane security in its area of strategic interest.

The economic implications for Australia are substantial. The treaty is expected to catalyze significant investment in Australia’s defense industrial base, creating thousands of high-skilled jobs and establishing new manufacturing capabilities.

The Australian government has already committed nearly AUD 250 million to develop the necessary workforce, including providing 4,001 Commonwealth Supported Places at Australian universities and 3,000 undergraduate scholarships over six years to build the required science, technology, engineering, and mathematics workforce.⁵

Implications for the United Kingdom

For the United Kingdom, the Geelong Treaty reinforces its position as a leading naval power and demonstrates its commitment to maintaining a global defense posture post-Brexit. The agreement is projected to support over 21,000 UK jobs and generate up to £20 billion in export potential, providing a significant boost to Britain’s defense industry.⁶

The treaty also represents a strategic investment in the UK’s submarine industrial base. The agreement includes plans for major expansion of industrial capabilities at BAE Systems Submarines in Barrow and Rolls-Royce Submarines in Derby, with new submarines scheduled to be built every eighteen months.⁷ This increased production capacity not only serves the AUKUS program but also strengthens the UK’s ability to maintain and modernize its own nuclear submarine fleet.

From a technological perspective, the shared development of the SSN-AUKUS design between the Royal Navy and Royal Australian Navy creates opportunities for innovation and cost-sharing that benefit both nations. The collaboration allows for the pooling of research and development resources, potentially accelerating technological advances that might otherwise take decades to achieve independently.

The treaty also reinforces the UK’s “Global Britain” strategy, demonstrating its commitment to the Indo-Pacific region and its role as a reliable security partner. This is particularly significant as the UK seeks to maintain its global influence and relevance in an era of shifting geopolitical dynamics.

Implications for the United States

While not a direct signatory to the bilateral Geelong Treaty, the United States remains deeply invested in its success, as the agreement directly supports the broader AUKUS framework that serves American strategic interests in the Indo-Pacific. The treaty complements existing U.S.-Australia and U.S.-UK agreements and reinforces the trilateral nature of the AUKUS partnership.

However, the signing of the Geelong Treaty comes at a time of potential uncertainty for AUKUS under the Trump administration. The Pentagon has initiated a review of its role in the partnership to ensure alignment with President Trump’s priorities, with results expected by fall 2025.⁸ Despite this review, UK and Australian officials have expressed confidence that the new administration will renew its commitment to AUKUS, viewing the review as an opportunity for reaffirmation rather than retreat.⁹

For the United States, the Geelong Treaty represents both an opportunity and a challenge. On one hand, closer UK-Australia cooperation reduces the burden on American resources and demonstrates the maturation of alliance relationships beyond simple dependency on U.S. capabilities. The development of a shared UK-Australia submarine design could eventually lead to standardization benefits across all three navies, improving interoperability and reducing long-term costs.

On the other hand, the bilateral nature of certain AUKUS developments raises questions about the future structure of the partnership. As the UK and Australia develop increasingly independent capabilities, the United States may need to recalibrate its role from technology provider to equal partner, a transition that could prove politically and strategically complex.

Regional and Global Implications

The Geelong Treaty’s significance extends far beyond the bilateral relationship between Australia and the UK. In the context of rising tensions in the Indo-Pacific, particularly concerning China’s growing assertiveness in the South China Sea and broader regional ambitions, the treaty represents a substantial enhancement of Western naval capabilities in the region.

The agreement has already drawn attention from potential AUKUS Pillar II partners, with Japan, South Korea, Canada, and New Zealand all expressing interest in various forms of cooperation. The success of the bilateral submarine cooperation model established by the Geelong Treaty could serve as a template for future partnerships and alliance structures.

Critics, however, have raised concerns about the proliferation implications of transferring nuclear propulsion technology, even for peaceful purposes. The agreement includes explicit provisions ruling out uranium enrichment or spent fuel reprocessing in Australia, and reaffirms all parties’ commitment to non-proliferation obligations under international law.¹⁰

Challenges and Future Outlook

Despite its strategic significance, the Geelong Treaty faces several implementation challenges. The development of a skilled workforce capable of handling nuclear propulsion technology represents a generational undertaking for Australia. The country must build regulatory frameworks, safety protocols, and industrial capabilities from scratch, all while maintaining the highest standards of nuclear security and non-proliferation.

The timeline for the SSN-AUKUS program is ambitious, with the first submarines expected to enter service in the early 2040s. Meeting these deadlines will require unprecedented cooperation and coordination between the two nations’ defense industries, governments, and military services.

Financial sustainability also presents ongoing challenges. The total cost of Australia’s nuclear submarine program is estimated in the hundreds of billions of dollars over its lifetime, requiring sustained political commitment across multiple electoral cycles in both countries.

Conclusion

The Geelong Treaty represents a watershed moment in defense cooperation between Australia and the United Kingdom, establishing a framework for collaboration that will define their naval capabilities for the next half-century. While primarily focused on submarine development, the treaty’s implications extend far beyond naval affairs, touching on industrial policy, technological innovation, alliance relationships, and regional security architecture.

For both nations, the treaty offers the promise of enhanced capabilities, economic benefits, and strategic relevance in an increasingly complex global security environment. For the United States, it represents both an validation of the AUKUS framework and a test of alliance adaptability in an era of evolving great power competition.

As the three AUKUS partners work to implement this ambitious program, the Geelong Treaty stands as a testament to the enduring strength of democratic alliances and their capacity to adapt to new challenges. Its success or failure will have profound implications not only for the immediate participants but for the broader international system and the future of collective security in the Indo-Pacific region.

Footnotes

  1. AUKUS – Wikipedia, accessed August 2, 2025. https://en.wikipedia.org/wiki/AUKUS
  2. UK Government, “AUKUS trilateral statement: 8 August 2024,” August 7, 2024. https://www.gov.uk/government/news/aukus-trilateral-statement-8-august-2024
  3. USNI News, “U.K., Australia Sign Treaty Ahead of Developing New AUKUS Attack Boat,” July 30, 2025. https://news.usni.org/2025/07/30/u-k-australia-sign-treaty-ahead-of-developing-new-aukus-attack-boat
  4. Ibid.
  5. UK Government, “AUKUS statement: 26 September 2024,” September 26, 2024. https://www.gov.uk/government/news/aukus-statement-26-september-2024
  6. UK Government, “AUKUS treaty deepens UK-Australia defence partnership to generate £20 billion in trade and create 7,000 new jobs,” July 26, 2025. https://www.gov.uk/government/news/aukus-treaty-deepens-uk-australia-defence-partnership-to-generate-20-billion-in-trade-and-create-7000-new-jobs
  7. AUKUS – Wikipedia.
  8. USNI News, “U.K., Australia Sign Treaty Ahead of Developing New AUKUS Attack Boat.”
  9. Ibid.
  10. Australian Submarine Agency, “AUKUS agreement for cooperation on naval nuclear propulsion,” accessed August 2, 2025. https://www.asa.gov.au/aukus/aukus-agreement-cooperation-related-naval-nuclear-propulsion