Subsea cables have quietly become one of the most important pieces of strategic infrastructure on the planet. They carry intercontinental internet traffic across more than 1.3 million kilometres of cable and handle global data flows and daily financial transactions. Power cables on the seabed are just as critical: they connect offshore wind, wave and tidal farms to onshore grids and interconnect national power systems, directly affecting security of energy supply in Europe. The Joint Research Centre of the European Commission (JRC) now treats subsea cables, both data and power, as a single critical nervous system for the EU’s economy, society and defence.

When that nervous system is cut, even briefly, the effects cascade through everything from payments and logistics to intelligence sharing and military command‑and‑control. How to ensure security in such a complex environment?