Despite warnings from the United States and Europe against Russia expanding its current aggression in Ukraine further west, new intelligence has revealed that Russia may be doing just that in the North Sea. The body of water is located in between Scandinavia and the United Kingdom.

According to a joint report by public broadcasters in Finland, Sweden, Denmark and Norway, Russia has been gathering intel in the North Sea. The alleged goal is to sabotage European wind farms, gas pipelines, and internet and power cables.

According to Norwegian broadcaster NRK, at least 50 Russian ships have gathered intelligence in Nordic waters in the last decade. Swedish broadcaster SVT reported 27 Russian spy ships had been seen in Swedish waters. The BBC reported UK officials are aware of Russian ships moving in UK waters.

“We saw in recent months Russian actors tried to uncover how the energy system works in the North Sea,” General Jan Swillens told the BBC. “It is the first time we have seen this.”

The ships from Russia are reportedly mapping offshore wind turbines, underwater data cables and other pieces of infrastructure belonging to Europe and the UK in the North Sea. Some are carrying out underwater surveillance, mapping key sites for possible disruption to European communications and energy supplies.

Known as “ghost ships,” the report suggested the ships entered the North Sea disguised as fishing trawlers or research vessels. The ships would then switch off their automatic identification system, rendering them invisible to conventional tracking.

Russia’s ambassador to Norway told NRK any research being done by Russia was properly coordinated through diplomatic channels in accordance with international law.