Wire cutters How the world's vital undersea cables are being targeted

The lead-clad telegraphic cable seemed to weigh tons, according to US navy lieutenant Cameron Winslow, and the weather wasn't helping their attempts to lift it up from the seabed and sever it.

- Dan Milmo

"The rough water knocked the heavy boats together, breaking and almost crushing in their planking."

Eventually, Winslow's men managed to cut the cable with hacksaws and disrupt the enemy's communications by slicing off a 150ft section.

This was in 1898 off the coast of Cuba during the Spanish-American war. More than a century later, subsea communications cables remain a target during times of geopolitical tension.

On 17 and 18 November two undersea fibre-optic cables in the Baltic Sea were damaged in an act that the German defence minister, Boris Pistorius, said was probably sabotage. Swedish police have said a Chinese cargo carrier, Yi Peng 3, that was in the area is "of interest".

The geopolitical backdrop to the current threat is the Russian invasion of Ukraine, China's behaviour towards Taiwan and the Israel-Gaza war, but they have always been an obvious target.

The cables - as thick as a garden hose when laid in deep water - carry 99% of all international telecommunications traffic, with 530 submarine cable systems in service around the world, spanning more than 850,000 miles.