Sweden tracks Russian submarine in Baltic Sea amid rising tensions.

“A Russian submarine entered the Baltic Sea yesterday via the Great Belt,” a Danish strait, the Swedish military said in a statement.

The military confirmed that Swedish jet fighters and warships intercepted and began following the submarine in the Kattegat strait between Denmark and Sweden. “The operation is taking place in close collaboration with our allies, and we have a good overview of our immediate vicinity,” it added.

Heightened tensions since Russia’s invasion

Tensions over the Baltic Sea have sharply increased since Russia’s full-scale invasion of Ukraine in 2022. Swedish Prime Minister Ulf Kristersson said earlier this year that while Sweden was not at war, “there is not peace either.”

Sweden ended over two centuries of military non-alignment when it joined NATO in 2024, a move driven by concerns about regional security and Russian aggression.

Hybrid threats and infrastructure attacks

Kristersson also warned that the Baltic Sea region has been subjected to hybrid attacks including disinformation campaigns and damage to undersea infrastructure.

“The Russian threat is very likely long-term. As our defense must be,” he said.

In 2024, Finnish special forces boarded and seized control of a Russian shadow fleet oil tanker named Eagle S after it severed critical undersea cables in the Baltic Sea. The incident marked the first time Finnish forces had taken such action since World War II.

NATO’s Baltic Sentry mission

A recent “60 Minutes” investigation revealed that the Eagle S incident was not isolated. Western authorities suspect repeated Russian operations targeting undersea cables and pipelines. In response, NATO launched Baltic Sentry, an initiative deploying ships and aircraft to monitor and protect the region’s seabed infrastructure.