02 — What if
None of what follows is our analysis. It is reporting, court records and a parliamentary committee. We have linked every claim so you can check it rather than take our word for it.
On Christmas Day 2024 the tanker Eagle S dragged its anchor across the Estlink 2 power cable and four telecoms cables in the Gulf of Finland. Investigators later recovered a drag mark scored along the seabed for dozens of miles.
Five weeks earlier, two more cables had been cut in the Baltic — C-Lion1 between Finland and Germany, and a link between Lithuania and Sweden. Nothing exotic was required. A commercial vessel, a chain, and time.
The Russian vessel Yantar — officially an oceanographic research ship, equipped with deep-diving submersibles — has twice been tracked over British critical undersea infrastructure, in January and again in November 2025.
The Defence Secretary told the Commons the Royal Navy had changed its rules of engagement to shadow the ship more closely, deployed HMS Somerset and HMS Tyne, and surfaced a submarine alongside it as a deterrent. His message to Moscow: “we see you, we know what you're doing.” On the November transit the ship directed lasers at RAF pilots monitoring it.
This is the part that should worry a resilience officer most. Parliament's committee found that coastal radar covers only 22% of the UK's Exclusive Economic Zone, and that barely 10% of the UK's marine area has been mapped to modern standards.
Ship transponders can simply be switched off near sensitive sites. The acoustic sensing that can detect an anchor on the seabed stops working past the first repeater — roughly fifty kilometres from shore. Beyond that, the first sign of damage is usually the outage itself.
Repair is the quiet constraint. The committee heard that a major maintenance consortium runs about three repair vessels, and each can work one break at a time. A single accidental cut is routine. A coordinated set is not.
Add weather, add a queue, add the possibility that the area is not safe to work in, and the recovery time stops being measured in days.
Every estimate above assumes an orderly response. The committee's own conclusion was blunter: it said the UK has been too timid in defending this infrastructure, that it could no longer rule out UK cables being targeted, and that it was not confident the country could prevent such attacks or recover within an acceptable time period.
It warned that extensive damage could cause “catastrophic disruption, including failures in payment systems and supply chains, degraded communications, overstretched emergency responses, and unexpected cascading issues”.