Leaders of several Western countries have said leaks in two Russian gas pipelines are likely the result of sabotage, vowing a strong response as investigations continue. Swedish authorities sounded the alarm on Tuesday about leaks in the Nord Stream 1 and Nord Stream 2 pipelines – both of which run under the Baltic Sea near Sweden and Denmark, and have been major flashpoints in the energy war between Europe and Russia. Neither pipeline was in operation at the time the leaks were found, but both still contained gas under pressure. Seismologists detected underwater explosions near the pipelines on Monday, but it’s unclear if those are connected to the leaks. Swedish Prime Minister Magdalena Andersson said in a news conference Tuesday that the leaks were “likely a deliberate action” but “not an attack against Sweden.” However, she said Sweden’s defense forces were ready to adapt to the situation, while Swedish Defense Minister Peter Hultqvist said marine units would be made available “if considered necessary.” Other major European leaders echoed these comments; the Danish Prime Minister Mette Frederiksen said she sees the leaks as “deliberate actions,” while the Danish Energy Minister Dan Jannik Jørgensen said they could have been caused “by blasts.” Norway’s Minister of Petroleum and Energy Terje Aasland said information so far “indicates acts of sabotage.” On Tuesday evening, European Commission President Ursula von der Leyen said she had spoken with Danish leaders about “the sabotage action,” and that it is “paramount to now investigate the incidents, get full clarity on events and why.” “Any deliberate disruption of active European energy infrastructure is unacceptable and will lead to the strongest possible response,” she warned. The European Union said on Wednesday it was “deeply concerned” about damage to the two pipelines. “All available information indicates those leaks are the result of a deliberate act,” the bloc’s foreign policy chief Josep Borrell said, while promising to increase energy security efforts. US National Security Adviser Jake Sullivan also spoke with his Danish counterpart on Tuesday about the “apparent sabotage,” saying the US was supporting investigation efforts. Meanwhile, a Russian spokesman told reporters on Tuesday, “No option can be ruled out right now.” The leaks and energy war German, Danish and Scandinavian security authorities are now examining the leaks and trying to identify their cause, according to the German Economy Minister Robert Habeck, who added that Europe is able to protect its critical infrastructure. Authorities are keeping ships away from the area, citing the risk of leaked gas igniting over the water and in the air – but say there are few other security risks, since the leak will only affect the environment where the gas plumes are located. “The destruction that occurred on the same day simultaneously on three strings of the offshore gas pipelines of the Nord Stream system is unprecedented,” said the pipeline’s operator Nord Stream AG. “It is not yet possible to estimate the timing of the restoration of the gas transport infrastructure.” “The causes of the incident will be clarified as a result of the investigation,” it said, adding that pressure drops suggested there had been physical damage. The incident has sank any remaining expectations that Europe could receive gas via Nord Stream 1 before the winter, as gas prices soar and countries hunt for alternative energy supplies. Russia halted all gas supplies to Europe via Nord Stream 1 in August, blaming Western sanctions for causing technical difficulties – which European politicians say is just a pretext to stop supplying gas. The new Nord Stream 2 pipeline had not yet entered commercial operation. The plan to use it to supply gas was scrapped by Germany days before Russia invaded Ukraine.