I have no English sources on hand, but there have been multiple parcels found across Europe that contained firebombs. In one case, the bomb didn't go off mid-flight because the flight was delayed.
The heads of German intelligence agencies had their annual public hearing recently, making it very clear that Russia considers Germany an enemy. As far as I can tell, the response by our senior political figures has been deafening silence and inaction.
So Putin is not stupid at all. He is just counting on the continued indecisiveness of most western leaders.
The "Ready Player One" approach might also help.