German officials said on Tuesday they believe the damage to two underwater fiber-optic cables in the Baltic Sea was an act of sabotage, but they could not speculate beyond that.

Germany’s defense minister said damage to two fiber-optic cables on the sea floor appeared deliberate, but a culprit was not known.

European officials are looking toward Russia after two submarine internet cables in the Baltic Sea were suddenly disrupted in an apparent sabotage operation, just weeks after the United States warned that Moscow was likely to target critical undersea infrastructure.