The Finnish authorities said the tanker might be part of Russia’s shadow fleet, which emerged as a way to circumvent Western-imposed price caps on Russian oil transported by sea. The caps were introduced several months after President Vladimir V. Putin of Russia ordered the full-scale invasion of Ukraine in February 2022.

Finland on Thursday seized a ship carrying oil for Russia in relation to the recent cutting of an undersea cable connecting electricity to Estonia as concern mounts over ships disrupting power and

Finland’s leaders are calling for more NATO protection against alleged Russian sabotage of critical infrastructure.