A subsea telecommunications cable and gas pipeline running adjacently between Finland and Estonia were damaged in what may have been a deliberate act, the Finnish government said on Tuesday.

An investigation into the damage began on Sunday, according to a statement from the office of Sauli Niinistö, the president of Finland, which suspected the damage was likely the result of “external activity.”

The 77 km (48 miles) Balticconnector gas pipeline only entered into operation in 2020 to connect the Estonian and Finnish gas grids. It was shut on Sunday when network operators detected an unusual drop shortly before 2 a.m.

Due to the pipeline’s relative youth, the Finnish network operator Gasgrid Finland said a hole in the pipe was the only reasonable expectation for a drop in the pressure. Gasgrid warned the damage could take months or more to repair.

“It is likely that damage to both the gas pipeline and the communication cable is the result of outside activity. The cause of the damage is not yet clear, the investigation continues in cooperation between Finland and Estonia,” Niinisto’s office stated.

Jens Stoltenberg, NATO’s secretary general, said the alliance was sharing information regarding the damage with both of the alliance members, Finland having joined NATO in April and Estonia having been a member since 2004.

The country’s prime minister Petteri Orpo described the damage as “worrying” but stressed that in general Finland's energy supply remained stable, and that the damage to the telecommunications cable wouldn’t affect the country’s overall connectivity.

Orpo told a press conference on Tuesday that it was “too early to draw conclusions on who or what caused the damage,” despite the president’s office blaming “external activity.”

A Finnish government press release said that the damaged point in the pipeline has been identified. A report from tabloid newspaper Iltalehti cited a source saying that Russia was suspected of attacking the pipeline.

Orpo was asked directly about Russia’s potential culpability during the press conference. He said: “It is important that the matter is investigated thoroughly and that conclusions that go too far are not made at this stage.”

The national broadcaster Yle reported that, according to both Finnish and Estonian seismologists, no seismic activity indicating an explosion had been detected.

Markku Hassinen, the deputy chief of Finland's Border Guard, concurred that there had been no indications of an explosion. He added that many different government ships from different states, in addition to merchant ships and warships, are present in and usually transit the area.