Why is Kaliningrad at the center of a new Russia-NATO faceoff?

Why Kaliningrad, Russia's Exclave in Europe, Is So Strategic

Why is Kaliningrad at the centre of a row between Russia and Lithuania?

Putin makes visit to Kaliningrad near NATO's Poland & Lithuania

Inside Kaliningrad, Russia's exclave at the centre of EU sanctions row

Kaliningrad: A fox living quietly in the hen house

What is Prussia? | History, Location & Contributions