Against the backdrop of the war in Ukraine, the Baltic Sea has been the scene of a string of incidents involving damage to key energy and communications lines.
In the latest incident, an undersea cable between Latvia and Sweden was severed on January 26 amid suspicions that the incident was an act of sabotage, stoking fears of interference and putting a spotlight on Moscow's so-called shadow fleet.
Swedish authorities boarded the Bulgarian-owned vessel that was sailing from Russia and later launched a sabotage investigation into the ship's actions. Both Riga and Stockholm have said the damage to the undersea data cable was likely the result of external interference.
This follows other recent episodes where undersea pipelines and cables were damaged by ships traveling to or from Russian ports.
In December, an oil tanker linked to Russia's shadow fleet was suspected of damaging undersea links off the coast of Finland with a loose anchor. A month earlier, a Chinese ship was involved in a separate incident. Another Chinese ship traveling from Russia also damaged a Baltic gas pipeline in October 2023.
While investigations are ongoing, the incidents have raised alarm among European governments that Moscow could be targeting undersea infrastructure as part of a broader campaign of hybrid attacks.
"It's highly unlikely to have four incidents like this in a row. That's a pattern," said Frank Juris, a Tallinn-based fellow at the Sinopsis think tank.
A New Normal In The Baltic Sea
The recent incident highlights rising tensions in the Baltic Sea since Russia's full-scale invasion of Ukraine nearly three years ago.
Following the cable damage in December, the European Union threatened new sanctions against Moscow and NATO launched a new patrol and surveillance operation.
The incident was blamed on an oil tanker from Russia's shadow fleet -- which is made up of ships without clear ownership that carry embargoed Russian oil products.
While the international spotlight has focused on Russia's use of the shadow fleet to circumvent Western sanctions, the ranks of such ships have also swelled beyond tankers.
EU governments have warned about the increasing maritime risks involving these Russian vessels.
Earlier in January, a dilapidated ship loaded with 100,000 tons of oil said to be part of Russia's shadow fleet was stuck adrift off Germany's northern coast.
German Foreign Minister Annalena Baerbock blamed Moscow at the time, accusing Russian President Vladimir Putin of going around sanctions and threatening European security by "ruthlessly deploying a fleet of rusty tankers."
NATO Secretary-General Mark Rutte said the new Baltic mission would involve more patrol aircraft, warships, and drones. He added there was "reason for grave concern" over infrastructure damage, adding that NATO would respond by boarding and even potentially seizing vessels in future incidents.
German prosecutors are also still investigating the explosion of the Nord Stream gas pipelines between Russia and Germany that occurred in September 2022.
What Comes Next?
Swedish authorities have said that they will be working closely with their Latvian counterparts to investigate potential sabotage, but attributing such incidents has proved difficult.
While Moscow's denials of responsibility for the incidents have so far been greeted with skepticism by European officials -- German Defense Minister Boris Pistorius called the November damage an act of "sabotage" and Finnish President Alexander Stubb said the December incident was linked to Russia -- the investigations remain open.
Alexander Kalchev, the CEO of Navibulgar, the Bulgarian shipping giant that owns the ship seized by Swedish authorities said in a January 27 statement that it's possible that the vessel damaged the cable, but dismissed any deliberate sabotage, saying that the ship was caught in "extremely bad weather" and dragged its anchor along the seafloor.
The Chinese government provided a similar explanation when it notified Finland and Estonia nearly a year after the October 2023 incident involving a Chinese ship that damaged an undersea pipeline after dragging its anchor for several hundred nautical miles.
Most experts say that a ship dropping anchor and dragging it along the seafloor for an extended distance would be noticeable for a crew and push a ship off course.
"Dragging an anchor for such a long time seems highly unlikely to go unnoticed and to happen over an extended period," said Juris.
EU member states are expected to begin discussions over a new round of sanctions against Russia later this week, which will mark the bloc's 16th sanctions package since Moscow's full-scale invasion of Ukraine in February 2022.
Two EU officials told RFE/RL that 20 to 30 new ships believed to be in Russia's shadow fleet could be added to Brussels' sanctions list, among other measures.
The EU has already sanctioned more than 70 alleged shadow fleet ships. Both the United States and Britain also introduced new sanctions on January 10 against 180 ships believed to be part of the fleet.
