A former American national security adviser once called Kaliningrad, a Russian enclave sandwiched between the NATO members Poland and Lithuania, “a dagger in the heart of Europe.” The latest flare-up with Lithuania is not the first time Kaliningrad has been the locus of tensions. In 2016, about 70 nautical miles off Kaliningrad, two Russian Su-24 planes buzzed the American guided missile destroyer Donald Cook, simulating an attack and drawing protests from Washington. In another episode that same month, a Russian warplane intercepted an American reconnaissance plane at an unsafe distance over the Baltic Sea.