Stuart Peach said an attack on the cables could "affect both our economy and other ways of living"
The head of Britain's armed forces has warned there is a growing risk of a Russian attack on undersea communication cables.
Air Chief Marshal Stuart Peach said a successful attack on the UK's network would trigger an immediate and "potentially catastrophic" hit to the country's economy and "our way of life".
In his annual lecture to the Royal United Services Institute in Whitehall, the chief of defence staff said international trade and the internet would be crippled if cables were cut or destroyed.
He said: "In response to the threat posed by the modernisation of the Russian navy, both nuclear and conventional submarines and ships, we along with our Atlantic allies have prioritised missions and tasks to protect the sea lines of communication.
"This sounds like a re-run of old missions, actually as I'm about to say, it is very, very important that we understand how important that mission is for the North Atlantic Treaty Organisation (NATO)."
In addition to new ships and submarines, he warned Russia "continues to perfect both unconventional capabilities and information warfare".
He said: "There is a new risk to our way of life, which is the vulnerability of the cables that criss-cross the seabeds.
"Can you imagine a scenario where those cables are cut or disrupted, which would immediately and potentially catastrophically affect both our economy and other ways of living if they were disrupted?
"Therefore we must continue to develop our maritime forces with our allies with whom we are working very closely, to match and understand Russian fleet modernisation."
His warning follows a report by Conservative MP Rishi Sunak for right-leaning think tank Policy Exchange, which revealed such an attack would be a "crippling blow" to the country's security and economy, earlier this month.
The report found that while the greatest threat was posed by submarine warfare, fishing trawlers with deep-sea grappling hooks could also carry out an attack.
"The result would be to damage commerce and disrupt government-to-government communications, potentially leading to economic turmoil and civil disorder," it warned.
The annexation of Crimea in 2014 was highlighted in the report, with it saying Russia was "easily" able to cut all digital communications from the region.