EXPLAINER: Why Russia-Lithuania tensions are rising

New tensions between Moscow and the West are rising after Lithuania decided to halt the transport of some goods through its territory to the Russian region of Kaliningrad as part of European Union sanctions on the Kremlin.

The Kremlin warns it will retaliate against the sanctions, stemming from its invasion of Ukraine, in a way that will have a “significant negative impact” on the Lithuanian people, raising fears of a direct confrontation between Russia and NATO.

A look at why tensions are rising over Kaliningrad, a part of Russia on the Baltic Sea that is separated from the rest of the country:

RUSSIA'S WESTERNMOST TERRITORY

The Kaliningrad region once was part of the German province of East Prussia, which was taken over by the Soviet Union after World War II in line with the 1945 Potsdam agreement among the Allied powers. East Prussia's capital of Konigsberg was renamed Kaliningrad, for Mikhail Kalinin, a Bolshevik leader.

An estimated 2 million of Germans fled the territory in the final months of World War II, and those who stayed were forcibly expelled after hostilities ended.

The Soviet authorities developed Kaliningrad as a major ice-free port and a key center of fishing, encouraging people from other regions to move into the territory. Since the Cold War era, Kaliningrad also has served as a major base of Russia's Baltic fleet.

But since the collapse of the Soviet Union and the independence of the Baltic countries, Kaliningrad finds itself separated from the rest of Russia by Lithuania, Latvia and Estonia, now all NATO members. To the south is Poland, another NATO member.

MILITARY BASTION

As Russia's relations with the West have soured, Kaliningrad's military role has grown. Its location has put it in the forefront of Moscow's efforts to counter what it...