ANZUS at 75: Defence Guidelines could strengthen Australia’s deterrence
ANZUS at 75: Defence Guidelines could strengthen Australia’s deterrence
Australia and the United States should use the 75th anniversary of the Australia, New Zealand, United States Security Treaty (ANZUS) to develop bilateral Defence Guidelines that strengthen the credibility and coherence of Australia’s deterrence architecture.
Australia’s deterrence posture operates across three dimensions: self-reliant deterrence, regional collective deterrence and US extended deterrence. These have largely developed as distinct strands of Australian defence policy. As the region’s strategic environment is driving greater Australia–US and allied force integration, these deterrence strands are growing increasingly interconnected. How they should interact and reinforce one another through the alliance remains insufficiently articulated. Australia–US Defence Guidelines could fill this gap by translating the three dimensions into practical cooperation around roles and missions, capability development, bilateral planning and crisis coordination.
ANZUS turns 75 on 1 September. While ANZUS has not operated as a trilateral alliance since the mid-1980s, Australia continues to maintain separate alliances with the parties under the treaty. Today, a more dangerous and unpredictable strategic environment reinforces the need for these alliances to connect various engagement strands for purposeful objectives to meet the threat. Australia is already applying this logic to its alliance with New Zealand. In March, Canberra and Wellington signed a new closer defence relations statement, titled ‘Operationalising the Australia–New Zealand Alliance: ANZAC 2035’. The joint initiative provides a 10-year framework to operationalise the alliance through greater force integration, posture cooperation, combined planning and exercises, explicitly linking these efforts to regional security, crisis response and collective deterrence.
Other US alliances in the Indo-Pacific use Defence Guidelines to translate longstanding treaty commitments into practical defence cooperation and coordination efforts that include deterrence as a focus. Japan, South Korea and the Philippines each have bilateral guidelines with the US that build on longstanding mutual defence treaties while adapting their alliances to changing strategic circumstances.
The 2015 Guidelines for Japan–US Defense Cooperation establish an overarching framework for cooperation during peacetime and conflict. They connect alliance policy to roles and missions, bilateral planning, operational coordination and capability cooperation, enabling the allies to prepare and respond together. A key component is the Alliance Coordination Mechanism, which supports common situational awareness, information sharing and coordinated responses, including flexible deterrent options and actions to de-escalate, while retaining separate national chains of command. The value lies in doing the work beforehand by identifying responsibilities, authorities, logistics and coordination arrangements rather than beginning that process after a crisis has started.
The US–Republic of Korea and US–Philippines Guidelines perform similar functions. The US–ROK Defence Guidelines connect combined defence to operational planning, intelligence sharing, interoperability, exercises and institutionalised extended-deterrence consultation. The 2023 US–Philippines Bilateral Defense Guidelines explicitly seek to ‘modernize and strengthen’ the alliance by establishing common understandings of roles, missions and capabilities; strengthening bilateral planning; and coordinating capability development to increase combined capacity to resist coercion and deter aggression. In each case, Defence Guidelines translate longstanding treaty commitments into the practical requirements of collective defence and deterrence, including by signalling the credibility of allied resolve and capability.
A strong and modern Australia–US alliance remains vital to Australia’s security and regional peace and stability. For Australia, Defence Guidelines offer an opportunity to turn three increasingly connected dimensions of Australian deterrence into a more coherent and credible architecture. Australian strategy requires Defence to possess a self-reliant capacity to generate deterrence by denial. The 2026 National Defence Strategy (NDS) links increased self-reliance to Australia’s ability to employ and sustain credible military power in a crisis or conflict, including when allied support may be limited. But Australia doesn’t expect to deter every regional threat alone. Collective deterrence brings Australia’s capability together with those of the US and other partners. Australia’s geography, intelligence capabilities, joint facilities, interoperable military forces, logistics and role in supporting US regional force posture all add to the combined military power available to deter regional aggression or conflict and respond if deterrence fails. Extended deterrence serves a different purpose. As outlined in the NDS, Australia regards US extended nuclear deterrence as the ‘best protection against the increasing risk of nuclear escalation’. Yet extended deterrence has historically received far less public articulation and institutionalisation in the Australia–US alliance than in other US alliances.
Greater integration is making the boundaries between these dimensions less distinct. In a regional conflict, Australia could simultaneously generate its own deterrent effects, contribute to collective deterrence and rely on US extended nuclear deterrence. Nuclear coercion against Australia or US strategic signalling could also directly affect Australian options, decisions and operations. This creates an increasingly important conventional–nuclear connection and the need for crisis communication. Each dimension serves a different purpose, but they increasingly overlap as Australia becomes more integrated with US and allied forces. How they work together is not always clear. Australia–US Defence Guidelines could help connect these strands.
Australia and the US should use the 75th anniversary of ANZUS to consider bilateral Defence Guidelines as the next evolution in the alliance. They would not replace or reinterpret ANZUS or predetermine Australian participation in future contingencies. Instead, guidelines would modernise the treaty’s implementation and give the alliance’s growing defence integration greater strategic and operational coherence. Institutionalisation is more than alliance management. Defence Guidelines would strengthen the alliance’s institutional machinery in ways that enhance credible collective deterrence and defence.
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