That reality came into sharper focus last week at the Shangri-La Dialogue in Singapore, where Defence Minister Richard Marles warned that “the seabed is a battlefield” amid growing concerns over the vulnerability of global undersea infrastructure. The comments came alongside a major AUKUS announcement revealing Australia, the United States and the United Kingdom will jointly develop advanced underwater drone technology designed to help protect critical undersea infrastructure, including subsea communications cables. This reflects a growing recognition that the infrastructure underpinning Australia’s digital economy is becoming a strategic target.

The Invisible Infrastructure Behind Modern Australia

Undersea cables are often described as the backbone of the global internet. While satellites attract most of the public attention, more than 95 percent of international data traffic is transmitted through subsea cable networks connecting countries across the world. Australia relies heavily on these systems for everything from banking and healthcare to government operations and cloud computing. The challenge is that much of this infrastructure is difficult to monitor, geographically dispersed and vulnerable to both accidental and deliberate damage.

Recent incidents involving damaged cables in Europe, the Baltic Sea and parts of Asia have heightened international concern about how exposed these systems may be during periods of geopolitical tension. Governments and security agencies globally are increasingly treating subsea infrastructure as a critical national security asset rather than simply a telecommunications issue.

For Australia, the stakes are particularly high. As an island nation heavily dependent on international connectivity, disruption to key cable routes could have significant economic, operational and security consequences.

Why AUKUS Is Expanding Beneath the Surface

Much of the public conversation around AUKUS has focused on nuclear-powered submarines, but the latest developments show the partnership is increasingly extending into emerging technologies, autonomous systems and critical infrastructure protection.

The newly announced AUKUS project will see the three partner nations develop advanced uncrewed undersea vehicles (UUVs), with initial delivery expected from 2027. Defence leaders say the technology will support surveillance, monitoring and protection of underwater assets.

The move comes as governments face growing concerns about what security analysts describe as “grey-zone” activity, actions that sit below the threshold of open conflict but can still cause significant disruption. That includes sabotage, espionage, infrastructure interference and cyber-enabled operations targeting critical national systems. In this environment, undersea cables are increasingly viewed as both strategic assets and potential vulnerabilities.

Security Risks Are No Longer Just Cyber

One of the more interesting shifts happening across Australia’s security landscape is the growing overlap between physical security, cyber security and defence strategy. Traditionally, cyber resilience has focused on networks, endpoints and digital systems. Today, security planning is increasingly extending to the physical infrastructure that enables those systems to function in the first place.

Protecting data is no longer just about defending servers from attackers. It’s also about protecting the cables, facilities, supply chains and operational technology environments that keep information moving.

The Australian Government’s Cable Connectivity and Resilience Centre has already highlighted the importance of collaboration between industry, government and international partners to strengthen cable security and resilience as threats continue to evolve.

For organisations operating across critical infrastructure sectors, these discussions are becoming increasingly relevant, because a disruption to undersea communications infrastructure would not simply impact telecommunications providers. It could affect financial services, transport systems, healthcare providers, government agencies and major enterprises simultaneously.

A New Security Conversation

What stands out most about the recent AUKUS announcement is that it reflects a broader shift in how security threats are being viewed. National security is no longer confined to military bases or government networks. It now includes supply chains, cloud platforms, critical infrastructure, energy systems and the physical pathways through which digital information travels.

The seabed may seem far removed from the day-to-day concerns of security leaders, but as Australia becomes increasingly dependent on connected systems, protecting what sits beneath the ocean surface could become just as important as protecting what sits inside the network. And for many organisations, that conversation is only just beginning.

 ICYMI Australian News: Australia’s Foreign Policy Faces a More Complex Security Landscape 

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