Submarine communications cables

Submarine communications cables are the fibre-optic cables laid across ocean floors that carry the overwhelming majority of intercontinental data traffic. As the physical backbone of the internet and of global finance they are simultaneously a surveillance asset for states controlling their landing points, a chokepoint whose disruption degrades commerce, and a sabotage target in grey-zone competition.

Function

TeleGeography's cable map, checked on 30 July 2026, depicts a global system of active and planned routes rather than a fixed count of operating cables. Each system contains one or more fibre pairs between landing stations, with repeaters supporting long spans. Route, fibre-pair ownership, landing-station access, repair responsibility and traffic routing are different control points. A cable may be physically cut without severing all service if operators can reroute traffic, while a landing-station or power failure can disrupt an intact line. Repair time depends on location, weather, permits, fault identification and the availability of a suitably equipped vessel.

Strategic significance

Article 1 of the definitional spine lists major fibre-optic landing points among the strategic hubs of weaponised interdependence. Control confers two effects. The panopticon effect: a state with jurisdiction over cables and landing stations can observe the flows crossing them, the basis of large-scale communications intelligence. The chokepoint effect: cutting or degrading cables interrupts data, and therefore financial messaging, trading, and commerce, for the affected region. Because international finance rides on the same physical infrastructure, cable disruption is an economic weapon as much as an informational one. Ownership is itself contested terrain, with national-security scrutiny of Chinese participation in cable builds and landings reflecting the surveillance and dependency stakes.

These effects are conditional. Jurisdiction over a landing station does not grant visibility into every encrypted payload, and ownership does not necessarily confer day-to-day operational control. Traffic engineering may shift flows across another route, while capacity, latency and contractual access constrain substitution. A cut can cause no visible customer outage, or several simultaneous faults can overwhelm redundancy. Assessment must identify the route, fibre pair, operator, carried traffic and available repair plan before estimating economic effect.

Commercial maps describe architecture; they do not establish government access, wartime control or the cause of a fault.

Control or weaponisation history

Cable warfare is as old as the technology. In August 1914 Britain sent the cable ship Alert to cut German links, forcing traffic onto alternative routes, the case treated at The electric telegraph and cable networks (19th century). Incidents from 2023 to 2026 in the Baltic require separate treatment of damage, investigation, attribution and adjudication. An outage or vessel track does not prove sabotage or state direction. The EU Cable Security Toolbox published on 5 February 2026 emphasises risk assessment, route diversity, repair capacity and coordinated response. These are resilience measures, not findings about any particular incident.

See also

Fibre-optic landing stations and internet exchange points · Undersea cable cutting and sabotage capability · Weaponised interdependence · Baltic Sea subsea infrastructure incidents and security response, 2023-2026 · Economic statecraft

Sources

• EU 2026 cable-security toolbox
• ITU submarine-cable resilience body
• TeleGeography submarine-cable map
• International Cable Protection Committee recommendations
• UK National Archives account of cable operations in 1914