The 154 meter Russian nuclear submarine is powered by two nuclear reactors. It can be compared to a Swedish submarine that is 60 meters long and is powered by diesel electric motors.

- This is a very large submarine. It does not fit in the Baltic Sea. It is easy to track, says Niklas Granholm, research leader at the Total Defense Research Institute, FOI.

What does the submarine do in the Baltic?

- You can ask it. I don't know about that. One would imagine that there are exercises that will be done over the next few weeks.

- This is a very powerful weapon that enters the Baltic Sea.

Nuclear Torpedoes

It is known in the past that this type of submarine can carry 24 long range cruise robots equipped with nuclear warheads. But now FOI's Niklas Granholm states that it can also carry nuclear weapons torpedoes.

The weakest is 15 kilotons, which can be compared to the Hiroshima bomb. The heaviest, at 200 kilotons, is more than ten times as much.

- So that's big stuff. There are two types. The smaller one is for shooting smaller submarines that chase it. The bigger one I imagine is towards ships chasing it. And these cruise robots are designed to knock out long-range American aircraft carriers.

power Demonstration

Niklas Granholm says that the submarine is part of a new Russian pattern.

- Russia's military power should be demonstrated with maneuvers. It comes in and exercises a little and then you go home. Its role is mainly in the North Atlantic and the Barents Sea. It is a protection for the core strategic ability of the north.

Sister submarine Kursk before the accident that killed the entire crew of 118 people in 2000. Photo: EPA, Scapnix

At the same time, an accident would be devastating in the Baltic and the submarine class Oscar is the casualty.

Sister submarine Kursk dropped in 2000 after a torpedo exploded aboard and the entire crew of 118 people perished. Kursk was also an Oscar II class submarine. There have also been fires aboard Oscarubas.

- If there was to be a major accident with a nuclear-powered submarine with nuclear-charged torpedoes - then we have problems, says Niklas Granholm, research leader at Total Defense Research Institute, FOI.