TL;DR · 30-second read

The Short Version

Two of the undersea internet cables that link Australia to the rest of the world stopped working off Perth on the same weekend. Only 16 such cables connect the entire country.

At the same time, a tanker ship managed from the United Arab Emirates was tracked sailing back and forth in loops over the protected strip of seabed where the cables lie. The cable company says this could be coincidence and has asked federal police to investigate.

The bigger problem is that the cables had no built-in fault sensors. Nobody can say what broke them until a repair crew physically inspects them.

The Maritime Executive reported on August 13, 2026, that fiber operator Subco lost two subsea cables back-to-back over the preceding weekend. Both breaks occurred inside a government-designated cable protection zone off Perth, Western Australia. At about the same time, a UAE-managed product tanker (a ship that carries refined fuels) sailed an unusual racetrack pattern over the charted cable area and crossed it several times. Security consultancy Windward independently validated the vessel’s presence and identity.

Subco founder and CEO Bevan Slattery said the ship’s activity may be a coincidence. He nonetheless urged the Australian Federal Police to investigate urgently and said this could be the second such incident in a federally declared cable protection zone. The cables had no automatic diagnostic systems, so Subco will not know the root cause, including whether an anchor was dragged across the seabed, until it arranges a physical inspection.

Executive Summary

Australia’s international connectivity runs through 16 subsea cables, and two of them went down together off Perth. The breaks happened in a zone where anchoring and certain fishing are restricted precisely to protect cables. A tanker was moving back and forth overhead at the time, and surface conditions were benign. That combination made the operator raise the possibility of a security incident rather than treat the outage as routine maintenance.

The more consequential detail is operational. Because the cables lacked automatic diagnostics, Subco cannot yet tell an accidental anchor drag from deliberate interference. Anchor drag alone causes about a third of cable breaks worldwide, according to the International Cable Protection Committee. Until a repair ship reaches the fault, investigators, insurers, customers and policymakers have to act without knowing which kind of event this was.

For anyone running data centers or cloud services that depend on international routes, the difference matters. An accident is a random event that route diversity absorbs. A deliberate act can recur and can target several cables at once, and that changes how much redundancy is enough.

Two Out of Sixteen Is Not a Rounding Error

Subsea cables carry the overwhelming majority of intercontinental data traffic. That includes the traffic that lets Australian businesses reach cloud regions and AI services hosted overseas, and lets local data centers serve customers across the Indian Ocean and Asia. With just 16 cables linking Australia to the world, losing two at once removes a significant share of the country’s international paths. The Maritime Executive described that as a substantial security event.

Geography sharpens the problem. Perth is Australia’s western gateway, and cables landing there take routes toward Asia and the Middle East that east-coast systems do not. When two breaks cluster in the same protected corridor, traffic has to shift onto fewer routes. That can mean longer paths, higher latency (the delay data experiences in transit) and less spare capacity if anything else fails before repairs are complete.

The Real Gap: Nobody Can Yet Say What Happened

The detail that should concern infrastructure operators most is that Subco’s cables had no automatic diagnostic systems. Without them, the operator knows the cables stopped carrying light but not why. It has to send a vessel to locate the fault, lift the cable and examine the damage before it can distinguish an anchor strike from a snag, a fishing gear incident or deliberate cutting. Until then, the circumstantial evidence is all anyone has: back-to-back breaks, a ship making multiple crossings in a racetrack pattern, and calm surface conditions that remove bad weather as an easy explanation.

This attribution delay has direct consequences for data center and cloud operators. Resilience planning for subsea routes has traditionally assumed faults are independent accidents. Under that assumption, buying capacity on two or three diverse cables makes a simultaneous outage very unlikely. That math weakens if breaks can be deliberate and coordinated, because a single actor can hit several cables in one corridor, as two breaks in one protection zone illustrates. An operator that cannot tell which kind of event it is facing cannot tell whether its redundancy is adequate. It also cannot tell whether the same corridor is safe to rely on while repairs proceed.

The same gap slows everyone downstream. Police cannot easily build a case, insurers cannot assign a cause, and governments cannot calibrate a response. Slattery asked the Australian Federal Police to move urgently, and the physical evidence on the seabed is what any investigation will ultimately depend on.

Weighing the Evidence on Both Sides

The case for concern is real but circumstantial. The vessel’s track and timing match the breaks, Windward validated its identity and presence, and Slattery noted this could be the second incident in a federally declared zone. Researchers are also warning about the broader pattern. ASPI’s David Brewster told ABC that many recent cable cuts in Europe and around Taiwan were, in his view, fairly obviously the work of Russia and China. A new review from the Australian National University’s National Security College concludes that state actors appear to be probing cable infrastructure in peacetime so they could degrade connectivity quickly at the start of a conflict.

The case for caution is equally worth stating. Slattery himself twice said the ship’s behavior may be a coincidence. Anchor drag is a common, ordinary cause of cable damage. Brewster’s remarks concerned incidents elsewhere, not this one, and he acknowledged it is difficult to be certain in some cases. A tanker managed from the UAE is not evidence of any state’s involvement. Unusual vessel movements can have commercial or navigational explanations that have not yet been aired. The fair reading is that the incident warrants investigation, not that its cause is known.

What Operators and Buyers Should Take From It

For cable owners, the lesson is that monitoring is now part of the security posture, not just a maintenance convenience. Fault-location and fiber-sensing systems that can flag disturbances as they happen would shorten the window in which an event goes unexplained. Tracking vessel behavior over protection zones as it happens would help too. Protection zones deter accidental damage by lawful mariners, but they do not stop a ship that ignores them. Enforcement depends on noticing quickly.

For data center and enterprise buyers of international capacity, the practical questions are about correlation, not just redundancy. Are the backup routes physically separate from the primary ones, or do they share the same seabed corridor or landing point? How quickly can capacity be restored, and how many repair vessels are available in the region? Those answers now matter as much as headline bandwidth.

Background

Subsea cables are bundles of optical fiber laid along the seabed that carry most of the world’s intercontinental internet and data traffic. They are built to last decades but are physically exposed. Ship anchors and fishing gear are the most common causes of damage, and repairs require specialized vessels that are in limited supply. Australia’s geographic isolation makes it unusually dependent on a small number of these systems, and the government declares cable protection zones off major landing points to restrict risky activity near them.

Subco is an Australian subsea cable operator founded by Bevan Slattery, a long-time builder of Australian digital infrastructure. Concern about deliberate cable damage has grown since a series of incidents in the Baltic Sea and around Taiwan over the past several years. Security researchers there have pointed to state actors seeking disruption while keeping deniability, and that context is why every unexplained break now draws closer scrutiny.

Sources

Source: Suspicious Subsea Cable Breaks Prompt Calls for Investigation in Australia (The Maritime Executive): Subco reports two cable breaks off Perth coinciding with a tanker’s movements over a cable protection zone.