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.

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

The cable is called C-Lion1 and it runs 728 miles between Helsinki and Rockstock. It’s buried 3 feet into the seabed and would have been difficult to cut by accident. When it was laid down in 2016, it broke data speed records. The cable, just by itself, could enable everyone in Finland to jump on a 25Mbps internet connection at the same time.