They were in a restricted air space that they knew they weren't allowed to be in. This also isn't anywhere near the first time that Russia has flown/traveled into restricted areas, especially within that exact same space that is marked on that map. It's simple, if you trespass onto land multiple times and get warned by more than one NATO ally more than just a few times, along with all of your other acts of aggression towards other regions in the world (yes i'm referring to Ukraine) then you're just asking for trouble.