BRUSSELS (AP) — NATO Secretary-General Mark Rutte said Friday that the military alliance will step up patrols in the Baltic Sea region as Finnish investigators work to establish whether a ship linked to Russia sabotaged undersea cables there this week.

Finnish authorities seized control of the ship, the Eagle S, on Thursday as they tried to establish whether it had damaged a power cable linking Finland and Estonia and several data cables. It was the latest in a string of incidents involving the disruption of key infrastructure in the region.

In a post on X, Rutte said that he had spoken to Finland’s President Alexander Stubb “about the ongoing Finnish-led investigation into possible sabotage of undersea cables.” Rutte said that “NATO will enhance its military presence in the Baltic Sea.”

Asked for details about what might be done and when, NATO headquarters would say only that the 32-country alliance “remains vigilant and is working to provide further support, including by enhancing our military presence” in the region.

Finland, which shares a 1,340-kilometer (832-mile) border with Russia, joined NATO in 2023, abandoning a decades-old policy of neutrality.

In October 2023, in response to similar incidents, NATO and its allies deployed more maritime patrol aircraft, long-distance radar planes and drones on surveillance and reconnaissance flights, while a fleet of minehunters was also dispatched to the region.

The Eagle S is flagged in the Cook Islands but has been described by Finnish customs officials and European Union officials as being part of Russia’s shadow fleet of tankers shipping oil and gas in defiance of international sanctions imposed over its war on Ukraine.

The aging vessels, often with obscure ownership, routinely operate without Western-regulated insurance. Russia’s use of the vessels has raised environmental concerns about accidents given their age and uncertain insurance coverage.

The Eagle S’s anchor is suspected of causing damage to the cable, Finland’s Yle state broadcaster has reported, relying on police statements. Kremlin spokesman Dmitry Peskov was asked about the seizure on Friday but declined to comment.

After a high-level meeting about the incident, Stubb posted on X that “the situation is under control. We have no reason to be worried,” while adding that the investigation continues. He said that Finland and Estonia had requested extra NATO help.

He said new measures could include “inspections of the insurance certificates of vessels” in the region. Stubb added that “we are also looking at ways, based on international maritime law, to respond more effectively to similar incidents in the future.”

The Estlink-2 power cable, which takes electricity from Finland to Estonia across the Baltic Sea, went down on Wednesday but had little impact on services. The incident follows damage to two data cables and the Nord Stream gas pipelines, both of which have been termed sabotage.

Those data cables — one running between Finland and Germany and the other between Lithuania and Sweden — were severed in November. Germany’s defense minister said “sabotage” was the likely cause but he didn’t provide evidence or say who might have been responsible.

The Nord Stream pipelines that once brought natural gas from Russia to Germany were damaged by underwater explosions in September 2022. Authorities have said the cause was sabotage and launched criminal investigations.

NATO had already boosted patrols near undersea infrastructure after the Nord Stream pipeline was hit. Last year, it also set up a coordination cell to deepen ties between governments, armed forces, and the defense industry and better protect undersea installations.