New Battlefields: What Is The Threat To Underwater Data Cables?

From Cornwall dozens of undersea fibre optic cables head out across the globe.

Our oceans have become information superhighways thanks to the data cables laid across the sea bed. 

Yet they could be under threat. Last year, the Defence Secretary raised the possibility of countries like Russia targetting undersea communications.

At the southwesternmost tip of mainland Britain, the waves and rugged coastline hide a secret.

From Cornwall, dozens of undersea fibre optic cables head out across the globe.

They carry telephone calls but mainly unbelievably large amounts of data, hundreds of terabits a second. 

Undersea optical fibre cables
Some 400 undersea cables stretch around the world for about 1.5 million kilometres. 

The cables provide the bedrock of our modern connected world. Digital telecom systems expert, Professor Jim Norton, said "they are the backbone to the world's communications":

"97% of the world's communications go on optical fibre cables."

Most people think satellites carry all the data, but the truth is that this is mostly done by cables.

Optical Fibre Cables
Every social media post in the UK will travel to the US and back via Cornwall.

So how vulnerable are they and could a hostile state attack this network? 

"If you hit a significant number of the undersea cables, the world financial system wouldn't grind to a halt... It would stop dead, the economic damage would be huge", said Professor Norton.

"You would have to hit a lot of cables but a state actor could do that simultaneously."

On Porthcurno Beach in Cornwall, eight of the UK's 40 undersea fibre optic cables head out across the globe. 

Porthcurno Beach, Cornwall Optical Fibre Cables
Porthcurno Beach where the super high-speed cables are hidden under six feet of Cornish beach.

The beach is home to a small white building, the cable hut, which has now been turned into a museum.

Inside are the old copper cables that used to send and receive telegraph messages around the British empire from the 1870s until 1970.

Early attacks on cables happened during the First World War. "The first act of aggression from the British was to go cutting German telegraph cables", explains operations manager Steve Bladon.

"Which just meant we had control over all communications going in and out from under the water from western Europe." 

Porthcurno Beach Second World War
Porthcurno cable office was a critical communications centre and considered vulnerable to attack (Picture: Telegraph Museum Porthcurno).

During the Second World War and with the advent of long-distance bombing, the authorities knew that Porthcurno could come under attack.

 "The idea was to move it underground. We're in a valley with a big cliff beside us, it was tunnelled out, 15,000 tonnes of rocks taken out and the telegraph station was rebuilt inside that."

All messages until the end of the war were then processed underground. 

Porthcurno cable office
'Cable and Wireless Great Circle Map' by MacDonald Gill (Picture: Telegraph Museum Porthcurno).

The whole area was heavily protected by troops, with barbed wire and flamethrowers on the beach, surrounded by pillboxes.

There were even escape tunnels for the staff working underground, in the event of a raid by German commandos. 

Although the area was bombed many times, the protection measures worked and the telegraph system remained operational. 

Optical Fibre Cables Inside BFBS
The cables carry unbelievably large amounts of data, hundreds of terabits per second.

How could we protect the modern fibre optic network?

As island states, Australia and New Zealand rely heavily on their fibre optic international cables. 

Professor Norton said: "They declared zones around those cables, which are protected."

Any vessels that go near them need to inform the authorities and will be monitored. 

Another way in the deep ocean would be to fit sonar sensing devices to the cables. 

"There would be some warning if a submarine was trying to locate them," Professor Norton continues.

"There are a number of things we can do in defence but we don't use them yet."

Repair Optical Fibre Cables BFBS
Teams are always on standby to respond to a broken cable in the North Atlantic.

A necessary part of keeping the network operations is repairing damaged cables, so even if they were deliberately cut, they could be fixed.

In Portland, Dorset, a warehouse filled with cables acts as a stock for the various lines running across the Atlantic. 

Moored alongside is C.S. Sovereign a cable ship used for underwater installations and repairs.

This operation is, put very simply, an insurance policy for the undersea cable operators. 

The ship and stocks of cables are ready to repair any breakages, with around 200 call outs a year.

C S Sovereign Cable BFBS
C.S. Sovereign has around 200 call outs a year to repair broken cables.

Once dispatched, the ship has several options for retrieving a cable.

The old-fashioned, yet still effective, is to 'fish' for the cable. An exceedingly long rope with a grapple hook is used to bring it to the surface.

But Captain Paul Haines, ship's master and Royal Navy reservist, explains that they also have more modern tech.

This is in the shape of a remote submarine, or a Remotely Operated Underwater Vehicle (ROV).

"Having ascertained where that fault is, then we can either cut the cable with ROV with a cutter, grip it with a hydraulic gripper and then bring that end of the cable to the surface and onto the ship."

Undersea cable repairs
To repair cables, the glass fibers need to be fused together.

Eventually, when the broken section is cut out, a new cable can be spliced in and, with microscopic precision, the glass fibres fused together.

The team are always on standby to respond anywhere there is a break in the North Atlantic. 

But are they worried about hostile action?

"It would be very difficult to break into a cable to tap off the information", said Cable Survey Manager, Kevin Connor.

"There are multiple cables running between countries...

"You'd have to cut a lot of cables to cause a serious impact to one particular country." 

Optical Fibre Cables Inside
Even if a cable was deliberately cut, it would be fixed quickly.

The location of undersea cables is well listed to alert shipping, as anchors dragging and trawler nets are by far the most common cable damage culprits. 

Yet this visibility does enhance the risk of hostile action. 

As we have seen, it has happened before and some feel it could happen again. But, according to the experts, the UK looks well placed to repair any damage.