At the Shangri-La Dialogue in Singapore, Australia, the United Kingdom, and the United States announced the first flagship initiative under AUKUS Pillar II: the joint development and deployment of advanced uncrewed underwater vehicles (UUVs). The project represents a significant shift in allied maritime capability, promising greater persistence in surveillance, reduced operational costs, and improved awareness across vast areas of the Indo-Pacific.
Undersea Infrastructural Vulnerability
However, the same technologies that enhance underwater awareness may also reshape the security environment in ways that make critical undersea infrastructure more difficult to protect. In particular, the wider adoption of UUVs, may weaken the ability of states to monitor, attribute, and deter hostile activity in the subsea domain.
This matters because undersea infrastructure is central to the modern international system. Submarine cables carry the overwhelming majority of global data traffic and form the backbone of financial systems, government communications, and digital economies. For Australia, an island nation, this dependency is especially acute. As Defence Minister Richard Marles has noted, approximately 99 per cent of Australia’s international data flows through only 15 submarine cables.
At the same time, these systems remain difficult to secure. Cables span vast and remote stretches of ocean, often in areas where continuous monitoring is not feasible. This creates inherent vulnerabilities that cannot be fully mitigated through traditional surface-based maritime surveillance.
Recent incidents of suspected interference with subsea cables in Europe and the Indo-Pacific have sharpened concern about the resilience of this infrastructure. Whether through deliberate sabotage or ambiguous accidents, these events highlight the strategic importance of the seabed as a contested domain. Marles further stressed ‘the seabed is becoming a battlefield’, ‘we have seen a series of attacks against subsea critical infrastructure at a scale and frequency that is historically unprecedented’.
UUV Utilisation & Problems
It is in this context that the rapid development of UUVs must be understood. Systems such as Australia’s Ghost Shark program reflect a broader shift toward autonomous maritime capability. These platforms can operate at depth, remain deployed for long durations, conduct surveillance or mission tasks with minimal human involvement, and significantly lower costs.
For defence planners, this represents a clear operational advantage. However, it also alters the structure of the undersea environment itself.
As UUVs proliferate, the barrier to operating in the subsea domain decreases. Activity that once required large, crewed submarines or specialised naval assets may increasingly be conducted by smaller, more autonomous platforms. This lowers the cost of entry not only for advanced militaries, but a wider range of state and non-state actors.
The result is a more crowded and less transparent underwater domain. In such an environment, the problem is not only detection, but attribution.
Traditional maritime security frameworks rely on observable indicators of activity. Surface vessels can be tracked through radar, Automatic Identification System (AIS) data, and satellite imaging. Submarines and naval assets are limited by logistical footprints, port access, and supporting infrastructure. Even when activity is covert, attribution can often be inferred through movement patterns and platform identification.
Autonomous underwater systems disrupt this logic. Operating below the surface, untethered from identifiable crewed vessels, they reduce the visibility of intent and origin. In practice, this means that interference with subsea infrastructure—whether through mapping, surveillance, or physical disruption—may become significantly harder to attribute with confidence.
This creates a grey-zone dynamic in the subsea domain. Incidents affecting critical infrastructure may occur without clear evidence of responsibility, blurring the line between accident, negligence, and deliberate action. As attribution becomes even more uncertain, deterrence becomes weaker.
Legal Frameworks & Implications of UUV
Existing legal frameworks, including the United Nations Convention on the Law of the Sea (UNCLOS), provide general protections for submarine cables and related infrastructure. However, these frameworks were developed in an era when underwater activity was primarily conducted by identifiable state vessels and manned submarines.
They do not clearly account for autonomous systems operating with varying degrees of human oversight, nor do they provide robust mechanisms for attribution in cases of suspected interference. This gap between technological capability and governance structure is becoming increasingly consequential as autonomous systems proliferate across both military and commercial domains.
For Indo-Pacific states, including Australia and its regional partners, the implications are significant. The region’s economic growth is increasingly dependent on digital connectivity, while its strategic environment is becoming more contested. Undersea infrastructure sits at the intersection of both trends.
This creates a structural tension. The more important subsea systems become, the more attractive they are as potential targets. Yet at the same time, the ability to monitor and attribute activity in the subsea domain is becoming more difficult.
Australia’s investment in autonomous underwater systems is a rational response. However, capability development alone is insufficient. Military advantage in the subsea domain must be matched by governance arrangements that address the new accessibility and attribution problem.
One option is the development of a minilateral framework for subsea infrastructure security among Indo-Pacific partners. Such an arrangement could focus on practical cooperation rather than formal treaty structures, and might include shared monitoring of key submarine cable routes, joint seabed sensing and maritime domain awareness initiatives, and agreed protocols for assessing and attributing suspected interference.
It could also support coordinated responses to infrastructure incidents, reducing ambiguity following disruption and strengthening collective deterrence. Importantly, such a framework would not require immediate reform of global legal mechanisms, but could operate alongside existing structures such as UNCLOS.
Governance & Norms
The central challenge is that technological change is outpacing governance. Autonomous underwater systems are being developed and deployed faster than the international community is adapting the rules and norms that govern their use.
AUKUS Pillar II reflects a necessary investment in future capability. But it also highlights a broader policy gap: the lack of mechanisms to manage attribution and accountability in an increasingly autonomous undersea environment.
In the Indo-Pacific, where undersea infrastructure is central to both economic stability and strategic competition, this gap carries real consequences. The task for policymakers is not only to expand maritime capability, but to ensure that the rules, partnerships, and coordination mechanisms exist to support it.
Leo Miles is an independent analyst and Psychology and Criminology graduate from Swinburne University. His interests include public policy, international affairs, governance, and the institutions that shape social and economic outcomes.
This article is published under a Creative Commons license and may be republished with attribution.
