Poland has said that the risk of a military clash is the closest it has been since World War 2
Russian flew around 20 drones, it is being said at this time, that were armed into Polish territory, which resulted in NATO shooting down those drones. As it stands at the moment, Russia is denying attacking Poland, and it is still early in the investigations, but it is looking as though Russia may have been testing NATO defences.
You can see why Poland invoked NATO's Article 4 here
Russian flew around 20 drones, it is being said at this time, that were armed into Polish territory, which resulted in NATO shooting down those drones. As it stands at the moment, Russia is denying attacking Poland, and it is still early in the investigations, but it is looking as though Russia may have been testing NATO defences.
You can see why Poland invoked NATO's Article 4 here