Submarine cables carry the overwhelming majority of international internet traffic, financial transactions, and government communications, with industry bodies such as the International Cable Protection Committee (ICPC) estimating well over 95% of intercontinental data moves through them. Satellites, by contrast, handle only a small fraction. This concentration makes the roughly 1.4 million kilometers of seabed cable a critical—and lightly defended—piece of global infrastructure.
Security concerns fall into several categories:
- Accidental damage, historically the largest cause, mostly from fishing trawlers and ship anchors. Hundreds of faults are repaired each year.
- Sabotage and grey-zone activity, including suspected state-linked incidents such as the 2022 Nord Stream pipeline blasts (a power/gas analogue), the 2023 Balticconnector and Estlink incidents in the Baltic Sea, and the December 2024 severing of the Estlink 2 cable, after which Finnish authorities detained the tanker Eagle S.
- Espionage and tapping, a long-standing concern dating to Cold War operations such as the U.S. Navy's Operation Ivy Bells.
- Supply-chain and vendor risk, particularly around cable-laying firms and landing-station ownership. U.S. regulators (Team Telecom, now the Committee for the Assessment of Foreign Participation in the United States Telecommunications Services Sector) have blocked or rerouted several proposed cables involving Chinese firms, including the Pacific Light Cable Network's Hong Kong landing.
Legal protection rests primarily on the 1884 Convention for the Protection of Submarine Telegraph Cables and UNCLOS Articles 113–115, which require states to criminalize willful or negligent damage by their nationals or flagged vessels. Enforcement on the high seas remains weak. NATO established a Maritime Centre for the Security of Critical Undersea Infrastructure in 2024, and the EU released a cable-security action plan the same year. Repair capacity is highly concentrated in a small global fleet of cable ships, itself a strategic vulnerability.
Example
In December 2024, Finnish authorities boarded and detained the tanker Eagle S on suspicion of severing the Estlink 2 power cable and several telecom cables in the Gulf of Finland by dragging its anchor across the seabed.
Frequently asked questions
The 1884 Convention for the Protection of Submarine Telegraph Cables and Articles 112–115 of the UN Convention on the Law of the Sea (UNCLOS), which oblige states to criminalize willful or negligent damage by their nationals and flagged ships.
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