Following the Nord Stream attacks in September last year the alliance is boosting efforts to protect undersea infrastructure.
Tensions heightened again after Russia accused Ukraine of a botched assassination attempt on Vladimir Putin by launching drone attacks on the Kremlin – a claim Ukraine denies.
NATO’s intelligence chief David Cattler said on Wednesday: ‘There are heightened concerns that Russia may target undersea cables and other critical infrastructure in an effort to disrupt Western life, to gain leverage against those nations that are providing security to Ukraine.’
He confirmed Russians were patrolling the Atlantic and have stepped up activities in the North and Baltic Seas since the Nord Stream blast.
In response, NATO has increased the number of ships patrolling the North and Baltic seas and established a Critical Undersea Infrastructure Protection Cell.
This monitors Russian espionage under the command of Lieutenant General Hans-Werner Wiermann, a retired German military officer.
‘The Russians are more active than we have seen them in years in this domain,’ Mr Cattler added.
The yet unexplained explosions damaged the Nord Stream 1 and 2 pipelines and since then further threats have become the focus of public attention.
Cattler declined to speculate who was behind the Nord Stream attacks during his briefing in Brussels on Wednesday.
But he did say: ‘Russia is actively mapping allied critical infrastructure both on land and on the seabed.’
Meanwhile, a NATO official told The Times: ‘There are strong suspicions that cables or pipelines have been mined. Companies have their own highly classified information. We have a lot of suspicions.
‘Somewhere in Moscow, there are people sitting and thinking of the best ways they can to blow up our pipelines or cut our cables.
‘Our job is to make that a costly and futile endeavour. At least, to make it undeniable, lessening the appeal because it is then an act of war.’
While concerns grow over the security of cables, the west plans to build new wind parks in the North Sea which will be linked to the mainland by cables.
According to NATO, other undersea cables transport some 95% of internet traffic around the world at speeds of about 200 terabytes per second, with 200 of these 400 cables deemed critical.
NATO is monitoring Russian vessels equipped with sensors that can collect electronic or acoustic information from the seabed.
Spy ships can be identified by their antennae or unusual activity near critical areas.