NATO has started a new mission to improve surveillance of ships in the Baltic Sea after important undersea cables were damaged or cut last year.

NATO chief Mark Rutte said the mission, called "Baltic Sentry," will involve more patrol planes, warships and drones. He made this announcement at a summit in Helsinki, which was attended by all NATO countries around the Baltic Sea: Finland, Estonia, Denmark, Germany, Latvia, Lithuania, Poland, and Sweden. Rutte stated that NATO would increase its surveillance of Moscow's "shadow fleet"—ships that are used to transport embargoed oil items but have no clear owner—even though Russia was not specifically named as the cause of the cable damage.

Since Russia launched a full-scale invasion of Ukraine in February 2022, tensions between NATO nations and Russia have been steadily increasing. Rutte stated that "there is reason for grave concern" about the damage to the infrastructure. He went on to say that NATO would take a strong stance in the event of such mishaps, increasing the number of suspect ships that are boarded and, if required, seizing them. He indicated that he did not want to make "the enemy any wiser than he or she is already" and declined to provide further information about the number of assets that will participate in the Baltic Sentry effort, stating that this could alter on a regular basis. Rutte stated that "1.3 million kilometres (800,000 miles) of cables guarantee an estimated 10 trillion-dollar worth of financial transactions every day" and that undersea infrastructure is crucial not only for the supply of electricity but also because over 95% of internet traffic is secured via undersea cables.

NATO would do "what it takes to ensure the safety and security of our critical infrastructure and all that we hold dear," he wrote in a post on X. There has been a rise in unexplained damage to undersea infrastructure in the Baltic recently. The latest incident involved an electricity cable between Finland and Estonia being cut in late December. The Finnish coast guard boarded the oil tanker Eagle S, which was sailing under a Cook Islands flag, and guided it into Finnish waters. Meanwhile, Estonia sent a patrol ship to protect its undersea power cable.

On Monday, Risto Lohi from Finland's National Bureau of Investigation told Reuters that the Eagle S was about to cut a second power cable and a gas pipeline between Finland and Estonia when it was seized.

Estonia's Foreign Minister, Margus Tsahkna, said in December that damage to submarine infrastructure had become so common that it made people question whether the damage could still be considered "accidental" or just "poor seamanship." Tsahkna didn't specifically blame Russia. Sweden was not "naive," according to Swedish Prime Minister Ulf Kristersson, who stated on Sunday that the country was not making snap judgments or "accusing anyone of sabotage without very strong reasons." "The security situation and the fact that strange things happen time and time again in the Baltic Sea also lead us to believe that hostile intent cannot be ruled out." "There is little evidence that a ship would accidentally and without noticing it... without understanding that it could cause damage," he said.