On July 26, Australia and the United Kingdom signed a 50-year treaty over a nuclear submarine deal. The “Geelong Treaty,” named after the Australian city where it was signed, aims to bolster cooperation between the two nations and supplement the 2021 A.U.K.U.S. pact, under which the U.S. and Britain share nuclear-powered submarine technology with Australia. Amid the formal review by the Trump administration, two U.S. allies are likely to uphold the 2021 framework. As Washington reconsiders the deal, a two-party agreement is crucial to ensuring the deal’s survival and enhancing deterrence against China.
“It is as significant a treaty as has been signed between two countries since Federation,” said Australian Deputy Prime Minister Richard Marles on July 25. Additionally, John Healey, British Defense Minister, hailed the treaty: “This is a treaty to last 50 years…It’s a treaty to build the most powerful, the most advanced attack submarines our two navies have ever had…It’s a treaty that strengthens N.A.T.O. as well as security in the Indo-Pacific.”
The bilateral nuclear submarine partnership treaty supplements the A.U.K.U.S. partnership, which was signed in September 2021. The partnership aimed to support Canberra’s development and acquisition of a nuclear submarine, with the support of both the U.K. and the U.S. The scheme includes training for the Australian Navy, the development of the U.S. and U.K. nuclear submarine units in Australia in 2027, and the purchase of U.S. Virginia-Class submarines by the 2030s. A.U.K.U.S. seeks to deter China, especially its marine expansion in the Indo-Pacific region. However, some members of the Trump administration, including Defense Undersecretary Elbridge Colby, have called for reviewing the plan, citing the potential danger of transferring nuclear-related technology to the ally. Although the review was initially planned to last a month in June, its conclusion has not yet been published.
While nuclear-powered submarines are not equipped with nuclear weapons, Australia’s path toward advanced military capabilities mustn’t lead—intentionally or unintentionally—to future nuclear armament. Canberra has repeatedly denied the possibility of nuclear possession since the trilateral pact was made in 2021. Such a development would fundamentally alter the security dynamics of the Indo-Pacific and undermine global nonproliferation norms.
Fifty years might be enough to secure the treaty among the three nations, which will make Australia the seventh nation to possess nuclear submarines by the late 2030s. However, the most crucial component is the U.S.’s full commitment. Washington has been reviewing the A.U.K.U.S. pact for a month, citing concerns about the potential transfer of nuclear-related technology to the ally.
The Geelong Treaty is a part of broader attempts to hedge against Trump. In Europe, the UK and France issued the “Northwood Declaration” to cooperate with nuclear deterrence. Moreover, Berlin and London signed the friendship treaty to enhance their security. Both goals are not only countering Russia’s aggression in Ukraine, but also dispelling the uncertainty of Trump’s second administration, which might not defend allies in the wake of military conflicts. The Anglo-Australian pact might be a similar attempt in the Indo-Pacific.
Deterrence certainly plays a central role in many states’ security strategies, but it must not come at the expense of diplomatic engagement. Dialogue and deterrence must operate in tandem—only through balanced and transparent diplomacy can lasting peace in the region be achieved.
