Gas bubbles from the Nord Stream 2 leak reaching surface of the Baltic Sea in the area shows disturbance of well over one kilometre diameter near Bornholm, Denmark, September 27, 2022.
NATO Secretary-General Jens Stoltenberg said he discussed the "sabotage" of the pipelines at a meeting with Danish Defence Minister Morten Bødskov in Brussels.
"We addressed the protection of critical infrastructure in NATO countries," the chief of the Western military alliance that also includes most EU countries said on Twitter.
The EU, meanwhile, issued a strong warning to anybody attempting to attack the energy backbones of the 27-nation bloc.
Borrell announced the bloc would step up the protection of its energy infrastructure following the incidents.