General Mark Rutte says the military alliance will step up patrols in the Baltic Sea area as Finnish investigators work to establish whether a ship linked to Russia sabotaged undersea cables there this week.

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.

Finnish authorities seized the Russian oil tanker Eagle S after the country’s police opened a criminal investigation into the vessel’s possible involvement in another cutting of undersea power and communications cables in the Baltic Sea on Christmas Day,