How serious is the Russian spy ship move?

To Russia, the Yantar is an oceanic research vessel - to others, including the UK, it's a spy ship, and a worry for Britain's defence chiefs. This isn't the first time the Yantar has popped up near Britain's shores - at the start of the year a Royal Navy submarine made the highly unusual move to surface right in front of the ship as a sort of deterrent measure. The concern is that this is part of an ongoing operation by the Kremlin to locate and map all the vital undersea cables and pipelines that connect the UK to the rest of the world.