On 26 July, Australia and the UK signed a historic bilateral agreement in Geelong that significantly deepens their defence and technological cooperation under the AUKUS security pact.
The agreement, known as the Geelong Treaty, formalises the five-decade strategic partnership between the two countries, focusing on the joint development, production, and use of SSN AUKUS-class nuclear-powered submarines (nuclear-powered military submarines armed with conventional weapons, without nuclear missiles).
This is the longest bilateral defence treaty Australia has ever signed, and it is the first to explicitly provide for technological, infrastructural, and personnel integration with another country in the field of nuclear naval technology.
Although it fits within the broader framework of the trilateral AUKUS (Australia–UK–USA), the Geelong Treaty is based solely on the UK–Australia axis and operationalises what were previously only political statements.
The agreement was signed by UK Defence Secretary John Healey and Australian Defence Minister and Deputy Prime Minister Richard Marles in the presence of senior military and political delegations.
Healey described the agreement as "a Treaty for 50 years that will define the relationship between our two nations and safeguard the securities of our country for our children and our children's children", while Marles said it was "the biggest leap in Australia's military capability, really, since the formation of the Navy back in 1913".
Redefining roles within Western alliances
The agreement centres on cooperation in the development of a new class of submarines, the SSN-AUKUS, which will combine British design and American weapons technology. The UK plans to build these submarines at the Barrow-in-Furness shipyard, while Australia will build its own capacities at the Osborne naval shipyard in South Australia.
According to current estimates, Australia will invest around AUD 368 billion (approx. EUR 230 billion) in the entire AUKUS structure over the next thirty years, including procurement, infrastructure, and training. The UK expects exports of technology and components to Australia to generate more than £20bn in sales and create up to 21,000 new jobs in supply chains and shipbuilding.
The agreement provides for the permanent presence of British Astute-class submarines in Australia as part of the Submarine Rotational Force – West, based at HMAS Stirling near Perth. This rotation is already taking place, and the agreement institutionalises it and links it to future deliveries of SSN-AUKUS units.
Strengthening the AUKUS pillar without an American initiative adds legitimacy to the British-Australian relationship
While the US, as the third member of the AUKUS pact, is reviewing its own engagement in some areas of cooperation - particularly nuclear technology exports and intelligence sharing — the Geelong Treaty shows that the UK and Australia have no intention of slowing down.
On the contrary, the increasingly intense public messaging from London and Canberra implies that the partnership is institutionalising independently of the US administration.
For London, this agreement comes at a time when it is attempting to reaffirm the UK's global military and technological role, particularly in the Indo-Pacific region, where China is increasingly exploiting the vacuum created by Washington's changing priorities.
For Australia, this is a way to ensure the long-term strategic autonomy and greater operational capability of the navy regardless of political changes in the US.
Strengthening the AUKUS pillar without an American initiative adds legitimacy to the British-Australian relationship and sends a signal that regional stability can no longer depend solely on the American defence shield.
This autonomy has political and security implications but also provides scope for redefining roles within Western alliances.
Reactions to the Geelong agreement
One of the central issues in criticising this treaty — both domestically and internationally — is the question of monitoring nuclear technology.
Although neither side acquires the right to nuclear weapons, non-proliferation organisations point out that this creates a precedent for the transfer of military nuclear technology between non-nuclear states, which could open the door to future abuses in other regions.
British and Australian officials assure that everything is in accordance with the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) and that all activities are subject to inspections by the International Atomic Energy Agency (IAEA).
In addition, a special trilateral protocol on nuclear transparency was signed in 2022 (the so-called ENNPiA), which regulates the technical and legal aspects of cooperation within the framework of AUKUS.
Immediately after the signing of the Geelong Treaty, China condemned its signing as "an attempt to militarise the Indo-Pacific", while official Beijing stated that "the agreement undermines regional trust and destabilises the existing security framework".
An additional support for the balance of power in the region
Malaysia and Indonesia also expressed concern about the potential proliferation of nuclear technology, despite its intended use only for propulsion.
France, which lost a multibillion-dollar contract with Australia for conventional submarines in 2021, has made no secret of its frustration with the way cooperation with the US and UK has been organised.
Japan and India, on the other hand, reacted positively to the deepening of British-Australian cooperation, seeing it as an additional support for the balance of power in the region, especially against the backdrop of increasingly present Chinese military pressure in the South China Sea and the Taiwan Strait.
The future of AUKUS
If the implementation of the Geelong Agreement goes according to plan, Australia should be able to build, operate, and maintain its own nuclear-powered submarines by 2040.
This would mark a radical leap in the country's technological independence but would also further consolidate British influence in the Indo-Pacific.
While AUKUS began as a trilateral idea, it has since evolved into a series of complex but stable axes, of which the British-Australian one is the most concrete - Anthony Albanese
This agreement presents the UK with the opportunity to export advanced military equipment and components, thereby securing its position in a region that is poised to become a crucial arena for global competition in the forthcoming decades.
The SSN-AUKUS programme can also serve as a model for future military-industrial alliances with other partners — such as Japan, Canada, or India.
The Geelong Agreement is not just a bilateral treaty on submarines. It is a political statement and a commitment to continuity at a time when alliances are increasingly vulnerable to external shocks and internal weaknesses.
While AUKUS began as a trilateral idea, it has since evolved into a series of complex but stable axes, of which the British-Australian one is the most concrete.
If the United States continues to slow down technology transfer, delay deliveries, or continues to calculate its role in the programme, the Geelong Treaty could become the very foundation of the future AUKUS structure — based on the technical and political reliability of London and Canberra.
For the Western allies, this would mean a shift to a more decentralised model of security cooperation in which the major regional powers take the initiative.
For the Indo-Pacific region, it will be a direct test of whether the two states can independently develop and maintain a nuclear naval capability in the face of increasing strategic competition.
