Securing Critical Undersea Infrastructure in the New Age of Geopolitical Competition

Small Wars Journal | William Freer, Ellie Drake

Russia's Main Directorate for Deep-Sea Research intensified seabed reconnaissance in the Atlantic throughout 2025, culminating in a November 2025 incident where the vessel Yantar targeted British maritime surveillance aircraft while mapping Critical Undersea Infrastructure. These undersea vulnerabilities threaten network nodes carrying 97% of global telecommunications and £1.15 trillion in financial transactions, including 60 cables responsible for 99% of British data traffic.

The Department for Science, Innovation and Technology faces severe operational exposure given that current cable repair responses average eight days and depend entirely on commercially owned foreign-registered vessels. Mitigating potential sub-threshold sabotage requires integrating artificial intelligence threat-detection systems aboard naval assets like RFA Proteus alongside expanding joint NATO and European Union repair hubs. Establishing effective legal deterrence demands updating archaic governance under the 1884 Cable Convention and 1982 United Nations Convention on the Law of the Sea while extending national penal jurisdiction across Exclusive Economic Zones to criminalize subsea hybrid warfare.

Comment

The jurisdictional framework governing subsea telecommunications creates a legal asymmetry that favors sub-threshold disruption over active defense. Under the 1982 United Nations Convention on the Law of the Sea, coastal state authority within the Exclusive Economic Zone remains restricted regarding foreign-flagged civilian vessels engaged in dual-use seabed mapping. This statutory limitation prevents sovereign forces from taking pre-emptive enforcement action against vessels operating in international waters until deliberate physical interdiction occurs.

Extending domestic statutes like the United Kingdom's National Security Act 2023 to offshore EEZ boundaries introduces severe enforcement frictions with international maritime law. Establishing penal jurisdiction over foreign-registered survey craft requires overcoming sovereign immunity provisions historically protected under the 1884 Cable Convention. Attempts to enforce sabotage penalties beyond territorial waters without amending the 1982 UNCLOS framework will trigger diplomatic challenges from flag states shielding deep-sea survey operations.

Strategic Question for Discussion

If coastal states unilaterally expand domestic legislation like the UK National Security Act 2023 into Exclusive Economic Zones, does that effectively deter subsea mapping, or does it erode the freedom of navigation principles anchored in the 1982 UNCLOS framework?

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