Australia and the United Kingdom have formalised a landmark 50‑year bilateral defence pact, marking the most significant security accord between the two nations since Australia’s federation in 1901. Signed on July 26, 2025, in the Victorian city of Geelong by Australian Defence Minister Richard Marles and UK Defence Secretary John Healey, the agreement aims to deepen cooperation under the broader AUKUS framework and secure regional stability in the Indo‑Pacific.
The agreement, dubbed the “Geelong Treaty,” lays the foundation for joint design, construction, operation, sustainment and eventual disposal of next-generation nuclear-powered attack submarines—known as the SSN‑AUKUS class—for both the Royal Navy and the Royal Australian Navy. Australia is expected to acquire at least eight submarines: several U.S. Virginia-class boats in the early 2030s, and entirely domestically built SSN‑AUKUS vessels produced in Adelaide from the 2040s onwards.
Officials highlighted the deal’s strategic and economic impact on both countries. The UK government estimates up to £20 billion in exports to British defence industry supply chains over the next 25 years, in sectors centred on Barrow-in-Furness, Derby and other industrial centres. At its peak, the project is expected to support over 21,000 jobs in the UK, while Australia anticipates creating tens of thousands of high‑skilled jobs—Marles described it as the country’s largest ever industrial undertaking. The UK Ministry of Defence projects more than 7,000 new roles directly associated with submarine construction and R&D.
The treaty arrives at a moment of uncertainty for the trilateral AUKUS partnership. The U.S. administration, under former President Trump, has launched a review of Pillar I of AUKUS—the component involving Australia acquiring U.S. Virginia-class submarines—leading both Canberra and London to send a resolute message of continuity and support for the partnership. Despite the uncertainty, Australian and British defence officials expressed confidence that U.S. commitment will endure.
Financially, Australia has already transferred USD 1.6 billion to U.S. and U.K. submarine industrial bases, moving toward its goal of USD 2 billion in related investments by the end of 2025. The entire AUKUS investment under defence pact is projected to cost Australia between USD 268 billion and USD 368 billion over several decades of build, operations, and sustainment.
In parallel with the defence pact signing, the UK Carrier Strike Group, including the aircraft carrier HMS Prince of Wales, arrived in Darwin for Exercise Talisman Sabre. Over 35,000 personnel from 19 countries are participating in the largest military drills Australia has ever hosted, underscoring growing cooperation with the UK—even as the U.S. anchors the trilateral alliance. Minister David Lammy emphasised that the deployment symbolises Britain’s enduring presence and commitment to a free and open Indo‑Pacific.
Australian and UK leaders at the ministerial consultations known as AUKMIN reaffirmed their long-term vision for Pillar II of AUKUS—collaboratively developing capabilities in undersea warfare, AI, quantum technologies, hypersonics, cyber, and electronic warfare—while also coordinating joint workforce training, industrial base development, and enhanced interoperability across the alliance.
Despite optimistic rhetoric, analysts warn of risks if U.S. submarine deliveries fall behind schedule, potentially causing a capability gap for Australia. The UK has meanwhile committed to building a continuous submarine production pipeline, with plans to deliver the first SSN‑AUKUS submarines by the late 2030s and eventually expand its fleet to as many as twelve vessels. Observers caution that delays, cost overruns, or industrial bottlenecks could undermine the ambition if not managed carefully.
In spite of these uncertainties, both governments position the Geelong Treaty as a decisive reaffirmation of their strategic alliance, a catalyst for economic growth through defence industrial expansion, and an anchor for long-term regional security in the Indo-Pacific for decades to come.
