The threat of Russian operations against Finland's critical infrastructure "has increased" since the country joined NATO, the Finnish intelligence service said Thursday as Helsinki investigates potential sabotage of its natural gas pipeline.
"The threat of espionage and influencing operations against critical infrastructure has increased," Antti Pelttari, the director of the Finnish Security Intelligence Service (Supo), told reporters at a press conference.
Relations with Moscow have "significantly deteriorated" following Finland's accession to NATO in April, and Russia is "prepared to take measures against Finland," Supo said in its annual security review.
The Nordic country is currently investigating a leak that led to the shutdown of the Balticconnector natural gas pipeline from Estonia to Finland on Sunday, with officials saying it was most likely caused by "external" action.
When asked about potential Russian involvement, Pelttari refused to speculate but said "involvement of a state actor cannot be excluded."
The Finnish government has cautioned against drawing conclusions before all information about the incident has been gathered.
News of the pipeline's breach has raised questions, as it comes a year after blasts breached the Nord Stream 1 and 2 pipelines, which carry natural gas from Russia to Western Europe.
Despite the Balticconnector shutdown, operator Gasgrid said Finland's gas system was stable, with the supply of gas secured through liquefied natural gas imports.
Gasgrid said on Wednesday it would take at least five months to repair the pipeline.
Finnish intelligence services said operations to cripple the country's infrastructure remained "unlikely in the immediate future" and that any potential Russian operations would be mainly aimed at deterrence.
"The energy sector is one example of an effective target in this respect," said Suvi Alvari, an analyst from Suno.
Finnish authorities have urged organizations and companies responsible for critical infrastructure to raise their level of preparedness.
NATO chief Jens Stoltenberg on Wednesday pledged a strong response from the military alliance if information regarding damage to the Balticconnector pipeline reveals that it was a "deliberate attack."
Both Finland and Estonia are NATO members.