Air Chief Marshal Sir Stuart Peach, the chief of the defence staff, said Britain and Nato needed to prioritise protecting the lines of communication.
He said it would “immediately and potentially catastrophically” hit the economy if they were cut or disrupted.
The cables criss-cross the seabed, connecting up countries and continents.
- Could Russian submarines cut off the internet?
- How much of a threat does Russia pose?
- Four facts about undersea cables
The world’s submarine network comprises an estimated 213 independent cable systems and 545,018 miles (877,121 km) of fibre, according to a recent report for the Policy Exchange think tank.