NATO is stepping up patrols in the Baltic Sea following recent damage to undersea infrastructure in the region, the transatlantic military alliance said Thursday.

“The increased measures include additional surveillance and reconnaissance flights, including with maritime patrol aircraft, NATO AWACS planes and drones. A fleet of four NATO minehunters is also being dispatched to the area,” NATO said in a statement.

The move followed announcements by authorities of damage to a Baltic Sea telecom cable connecting Sweden and Estonia and to a Finnish-Estonian pipeline and cable at around the same time earlier this month.

Officials from the countries involved have said they have yet to reach firm conclusions on who caused the damage or whether it was accidental or deliberate.

“We continue to monitor the situation closely, and we remain in close contact with our Allies Estonia and Finland, and our partner Sweden,” said NATO spokesperson Dylan White.

“NATO will continue to adapt its maritime posture in the Baltic Sea and will take all necessary steps to keep Allies safe.”

The buildup illustrates that NATO allies are vigilant and ready for action, Estonian Defense Minister Hanno Pevkur said.

“The decision does not mean that there is an increased military threat. Instead, it shows that relations between Allies are strong, and NATO as a whole sees the protection of critical infrastructure as an important issue,” he added.

Two of the four minehunters are expected to visit Tallinn on Friday.

NATO, the European Union and national governments have made protection of undersea pipelines and cables a high priority since explosions in September 2022 ruptured the Nord Stream pipelines under the Baltic Sea and cut Europe’s supply of Russian gas.

Investigators have said those blasts were an act of sabotage but have not yet decided who was responsible.