Introduction

Russia’s recent deployment of a conventionally armed, diesel-powered submarine to Indonesia should not be dismissed as routine naval activity. It is a calculated strategic signal. One that highlights a growing challenge for Australia and calls into question the resilience of U.S. extended deterrence in the Indo-Pacific. While such deployments fall below the nuclear threshold, they reveal an emerging approach to strategic competition. The use of advanced conventional capabilities can undermine the systems that enable nuclear deterrence.

At the center of this challenge is the vulnerability of U.S. nuclear command, control, and communications (NC3) architecture. Facilities in Australia, including Pine Gap and Naval Communication Station Harold E. Holt, are integral to this architecture. They support early warning, signals intelligence, and communications with nuclear forces. As such, they are not only strategic assets but also potential targets. Modern diesel-electric submarines—quiet, survivable, and increasingly capable—can operate in Australia’s northern approaches and threaten these critical nodes with precision strike options or intelligence-gathering missions that enable future disruption.

The Gray Zone Effect

This development reflects a broader shift in adversary strategy. Rather than relying on overt nuclear coercion, states such as Russia are exploring how to achieve strategic effects through conventional means. By targeting NC3 infrastructure using submarines, cyber operations, or long-range precision strike, adversaries can degrade the credibility of nuclear deterrence without crossing the nuclear threshold. This approach exploits the grey zone between peace and war, complicates escalation dynamics, and introduces ambiguity into alliance responses. It is not escalation dominance in the traditional sense, but escalation manipulation, and shaping the environment so that nuclear deterrence becomes less certain, less credible, and therefore less effective.

Recent Chinese naval activity reinforces this concern. The PLA Navy’s circumnavigation of Australia should not be viewed as routine presence or symbolic signaling alone. Rather, it demonstrates an emerging capacity to operate persistently along Australia’s littoral approaches and key maritime choke points—areas proximate to critical infrastructure that underpins U.S. and allied NC3. Such operations enable the mapping of undersea terrain, surveillance of communication pathways, and potential identification of vulnerabilities in systems such as subsea cables and relay nodes. In a crisis, these capabilities could be leveraged to conduct limited, deniable disruption of NC3 functions that degrade communication, delay decision-making, and complicate alliance coordination without crossing the threshold of armed attacks. In this sense, China’s activity mirrors and reinforces the broader trend: the use of conventional means to hold at risk the foundations of nuclear deterrence.

For Australia, the implications are significant. The traditional model of U.S. extended deterrence, anchored in the threat of nuclear retaliation, assumes that nuclear forces remain survivable, communicable, and politically usable. However, if NC3 systems are degraded or disrupted, that assumption weakens. Deterrence begins to erode not because nuclear weapons are absent, but because their employment becomes uncertain or delayed. In such a scenario, adversaries may calculate that they can act with greater freedom at the conventional level, confident that escalation can be managed or avoided. 

Policy Recommendations

This evolving threat environment demands a recalibration of Australia’s defense and deterrence posture. Nuclear deterrence remains essential, but it is no longer sufficient on its own. It must be reinforced by a comprehensive strategy that integrates conventional resilience, grey-zone competition, and a more explicit recognition of the role nuclear forces play in underpinning deterrence across all domains.

First, Australia should prioritize the hardening and resilience of NC3-related infrastructure on its territory. This includes enhancing physical protection, investing in redundancy and dispersal, and strengthening cyber defenses. Facilities such as Pine Gap and Harold E. Holt must be able to operate under contested conditions, ensuring continuity of communication and decision-making even in the face of sustained disruption. This may also require the development of alternative communication pathways, including space-based and mobile systems. Resilience is not merely a defensive measure; it is a core component of deterrence, signaling to adversaries that attempts at degradation will not succeed.

Second, Australia must significantly expand its undersea surveillance and anti-submarine warfare (ASW) capabilities. The ability to detect, track, and, if necessary, neutralize hostile submarines in Australia’s maritime approaches is critical to protecting strategic infrastructure. Investments should focus on integrated undersea sensor networks, maritime patrol aircraft, autonomous systems, and closer operational integration with allies. A persistent and credible ASW posture will complicate adversary planning, increase operational risk, and reduce the feasibility of covert operations targeting NC3 nodes.

Third, Canberra should deepen strategic dialogue with Washington on the role of Australia within U.S. nuclear deterrence architecture. This dialogue must move beyond general assurances and address specific contingencies, including how attacks on NC3 infrastructure in Australia would be interpreted. Greater clarity around escalation thresholds, attribution challenges, and response options will reduce the risk of miscalculation and strengthen the credibility of extended deterrence. This should include regularized nuclear consultation mechanisms and scenario-based planning.

Fourth, Australia should take the lead in advocating for the development of an Indo-Pacific nuclear alliance. Such a framework that brings together the United States, Japan, South Korea, the Philippines, Papua New Guinea, and Australia, would formalize shared deterrence responsibilities and strengthen collective resolve. While politically sensitive, this arrangement could include elements of nuclear consultation, planning, and burden-sharing, similar in principle to NATO’s nuclear sharing arrangements. By distributing deterrence functions and signaling unity, such an alliance would complicate adversary calculations and reinforce the credibility of nuclear deterrence across the region.

Fifth, Australia must engage India more directly on the implications of Russian strategic behavior. As a key regional power with longstanding ties to Moscow, India occupies a unique diplomatic position. Canberra should clearly communicate its concerns regarding Russian military activities in the Indo-Pacific, including the risks posed to critical infrastructure and regional stability. In parallel, India should be encouraged to consider the broader consequences of a hypothetical Russian attack on Australia, not only for bilateral relations, but for its strategic partnerships with both the United States and Australia. This dialogue would not seek to force alignment, but to underscore the interconnected nature of regional security and the potential costs of strategic ambiguity.

Sixth, Australia should explore options to visibly anchor U.S. nuclear deterrence in the region. This necessitates a proactive approach to alliance integration. Mechanisms such as enhanced consultation, increased transparency around nuclear policy, and potential participation in nuclear planning arrangements could reinforce deterrence by demonstrating resolve and cohesion. Initiatives under AUKUS provide a foundation for this deeper integration and should be expanded to include broader deterrence considerations.

Seventh, Australian defense policy must explicitly recognize the interdependence of conventional and nuclear deterrence. Investments in long-range strike, cyber capabilities, and undersea warfare are essential, but they must be understood as part of a broader deterrence framework. These capabilities contribute to resilience and denial, but they are ultimately underpinned by the threat of escalation. Ensuring that this relationship is clearly articulated in strategy and doctrine will strengthen deterrence coherence and improve signaling to adversaries.

Finally, Australia must broaden its strategic focus to account for multiple nuclear-capable adversaries operating in the Indo-Pacific. While China remains the primary focus of defense planning, Russia’s increased presence in Southeast Asia underscores the need for a comprehensive approach. Strategic competition is no longer confined to a single actor or domain. It is multi-faceted, simultaneous, and increasingly coordinated. Australia’s deterrence posture must reflect this complexity.

Conclusion

The central lesson is clear. Deterrence in the 21st century cannot be treated as a layered system in which nuclear weapons sit passively at the top. Instead, nuclear deterrence must actively underpin and reinforce every level of conflict, including the conventional and grey-zone domains. Adversaries are increasingly seeking to exploit gaps between these layers, using conventional means to achieve strategic effects without triggering nuclear retaliation.

To respond to this challenge, Australia must take seriously the credibility of the nuclear deterrent on which it relies. This means investing in the resilience of critical systems, strengthening conventional capabilities, and engaging more deeply with allies and partners on the role of nuclear alliances and forces in regional security.

In an era defined by ambiguity and threshold management, the effectiveness of deterrence will depend on integration, clarity, and resolve. By advancing new nuclear alliance structures, deepening strategic dialogue, which includes India, and reinforcing both conventional and nuclear pillars of deterrence, Australia can ensure that sophisticated conventional threats do not undermine the stability of the broader strategic order.

Natalie Treloar is the Australian Company Director of Alpha-India Consultancy, a Senior Fellow at the Indo-Pacific Studies Center (IPSC), a Senior Analyst at the National Institute for Deterrence Studies (NIDS), and a member of the Open Nuclear Network. Views expressed are the author’s own.

Silent Signals: Russian and Chinese Conventional Threats to NC3 and U.S. Extended Deterrence in Australia was originally published on Global Security Review.