Red Sea cable cuts: Subsea cable repairs are 'not an easy fix'

Subsea cable repairs are not an easy fix, according to The Internet Report podcast.

For one, it's never a straightforward (or one-size-fits-all) task.

The process itself is highly complex, typically costing typically millions of dollars. It demands not only technical expertise but also significant resources.

Adding to the challenge is the scarcity of specialised vessels and equipment — only a handful of companies worldwide have the capability to carry out such operations.

The September 6 Red Sea cable cuts, for instance, happened in a geopolitically sensitive region.

This makes submarine cable repair a race against multiple obstacles at once, the report added.

Red Sea cable chaos

On September 6, 2025, several fibre-optic submarine cables in the Red Sea were reportedly severed. This cause widespread internet disruptions.

The failures were traced to a location near Jeddah, Saudi Arabia.

Cybersecurity firm NetBlocks confirmed degraded connectivity in countries such as India, Pakistan, Saudi Arabia, the UAE, and Kuwait.

In the UAE, major networks like Etisalat and Du faced significant slowdowns. Kuwaiti authorities reported direct impacts on the FALCON cable.

Submarine cables carry over 95% of global internet data traffic across nearly 1.5 million km of ocean floor.

Repairing vital links

These cables are vital yet vulnerable infrastructure.

Despite robust designs with protective armouring and burial in shallower waters, they face frequent faults — about 200 annually worldwide — from causes like ship anchors (70% of cases), fishing trawlers, earthquakes, or seabed abrasion.

What caused Red Sea cable cut? According to John Wrottesley of the UK-based International Cable Protection Committee (ICPC), investigations suggest the cuts were likely caused by “commercial shipping activity,” possibly a ship dropping and dragging its anchor across the cables. 

Cable repair: A step-by-step overview:

#1. Detection and fault localisation

Cable systems are monitored 24/7 from landing stations at each end using network management software, according to The Internet Report podcast.

When a fault occurs — such as signal loss or increased latency (more delays) — technicians perform initial tests to isolate the affected segment. 

For precise location, spread-spectrum time-domain reflectometry (SS-TDR) sends low-power signals down the cable, analysing reflections from impedance changes to pinpoint the break within metres, even on live systems. 

This non-disruptive method avoids traditional reflectometry’s risks with high-voltage power conductors.

Once located, coordinates are shared with repair teams.

#2. Mobilisation of repair vessel

Consortiums (e.g., owners of international cables) contract specialised cable repair ships, like the 22 aging vessels in global fleets (e.g., Ocean Link or NKT Victoria).

These ships, positioned strategically worldwide and on 24-hour standby, carry spare cable segments, splicing gear, and dynamic positioning thrusters to hold steady in storms. Mobilization can take days; for instance, a January 2025 fault near Taiwan saw a vessel arrive weeks later. Power cables (e.g., for offshore wind farms) may use similar vessels but require additional deburial tools for their thicker, buried designs.

3. Grappling and recovery

The ship navigates to the site and deploys a grapnel — a heavy, multi-pronged hook — lowered via winch to snag the cable. In unburied deep-sea sections, this is straightforward; grapnels are dragged along the seabed for miles if needed.

For buried shallow-water cables (common near shores), a remotely operated vehicle (ROV) or mass flow excavation (MFE) tool uses high-pressure water jets to unearth the cable without damaging it.

The hooked cable is slowly winched aboard, often over a stern chute to manage tension (up to 10 tons).

One end is cut ahead of the fault, tested for continuity, and buoyed off at sea; the process repeats for the other side. Deep repairs, like a 6,200-meter fix post-2011 Japan earthquake, demand precise current compensation to avoid drift.

#4. Splicing and ceplacement

On deck, in climate-controlled workshops, technicians remove the damaged section (typically 1-5 km) and splice in a pre-manufactured spare using fusion splicing machines.

For fibre-optic cables, this fuses glass strands under microscopes for near-lossless connections (power cables usually involve waterproof connectors).

The splice is encased in protective sheathing, often with metal wrapping against sharks. Tests ensure signal integrity, low latency, and no packet loss. This phase is labour-intensive, requiring certified crews to handle radiation risks from repeaters or hazardous materials.

#5. Re-lowering and reburial

The repaired cable is paid out over the stern, carefully lowered to the seabed using buoys and tension controls to match original contours. In buried zones, an ROV reburies it via water jetting to the target depth (e.g., 1-2 meters). Final end-to-end tests from landing stations confirm full functionality.

Repair challenges

Repairs are a high-stakes, specialised operation involving global consortiums, dedicated vessels, and precise engineering to minimise downtime, which can cost millions per day. 

They could also face weather delays, pirate threats, or environmental hurdles.

The process typically takes 10-20 days, depending on location, weather, and depth (the deepest part of the Red Sea is estimated at 3,040m).

When will the Red Sea cables be restored?

It’s not possible yet to give a precise date. Based on past precedent, repair of the Red Sea cable cuts is expected to take weeks to possibly a few months, according to a Submarine Networks report.

A number of factors make the timeline uncertain: Availability of specialised repair vessels (there are very few globally), permitting and security, geopolitical constraint, weather, sea conditions, and logistical challenges at sea, according to Tom's Hardware.

There’s also the complexity of locating, retrieving, splicing, testing, and re-laying cable sections. Some industry observers project that in certain areas of the Middle East (e.g. UAE) disruptions could last up to six weeks before more stable service returns.

What the Sept. 6 cable cuts revealed

However, the September 6 Red Sea cable cuts revealed something more nuanced: while services experienced increased latency and some degradation, the Internet’s redundant paths kept traffic flowing.

The automatic rerouting wasn’t perfect or universal. But for many routes, packet loss remained negligible even as traffic took longer, more circuitous paths to reach destinations.

Organisations like the International Cable Protection Committee (ICPC) help in no small part in this regard: they gather the industry to boost cooperation, and enforce standards, including protection zones banning fishing.

One report states that increased investments (estimated at $3 billion) are needed for cable industry repair modernisation and to sustain efficiency.

Cooperation is key

In the end, the recent cable cut underscored both the fragility and resilience of the global internet.

While the disruption highlighted the enormous challenges of repairing submarine cables, it also showcased the value of international cooperation and planning.

This is the benefit of cooperation.

Thanks to redundancy built into multiple cable routes, the impact on global connectivity was kept to a minimum. This episode is a reminder that in an interconnected world, collaboration and foresight are the best safeguards against inevitable disruptions.