NATO countries don't or barely respond because subversion requires a response. Russia is constantly pulling low hanging fruit hoping for as much commotion, fear, etc. It's party of their destabilization and subversion tactics. This is why authorities are not loud, but calm & stoic. And it works, very few people around me are aware of the fact that Russia has blown up NATO ammunition depots, liquidated politicians and has spread bombs on mail flights. During WW2 the British had a great slogan: /Keep Calm and Carry On/. It actually helps the war effort, unlike public outcry, wild speculation & unrest.