Russia has warned Lithuania, a member of NATO, that it will "take action" if rail access to the Kaliningrad exclave is not restored.

After the Baltic nation restricted the transportation of sanctioned items via its borders, Moscow summoned Lithuania's top diplomat to present a protest.

Dmitry Peskov, a spokesperson for the Kremlin, told reporters, "The situation is more than serious," "This is a truly unprecedented decision. It is a violation of all rules."

The Russian foreign ministry characterized Lithuania's action as "openly hostile."

"If cargo transit between the Kaliningrad region and the rest of the Russian Federation via Lithuania is not fully restored in the near future, Russia reserves the right to take measures to protect its national interests," the statement read.

Kaliningrad, originally the harbor of Königsberg, the capital of East Prussia, was taken from Nazi Germany in April 1945 and surrendered to the Soviet Union following World War II.

It is home to the Russian Baltic fleet and is Russia's sole ice-free Baltic port, with a population of approximately 430,000.

It is surrounded by NATO members Poland and Lithuania and is cut off from the rest of Russia by water. Goods trains are bound for Kaliningrad travel via Belarus and Lithuania; Poland is not a transit point.

Lithuania stated that it was simply executing EU sanctions as part of a slew of actions meant to punish President Vladimir Putin for the invasion of Ukraine.

"Lithuania is not doing anything; European sanctions went into effect on June 17," stated foreign minister Gabrielius Landsbergis. It was carried out with consultation from the European Commission and per its directives.

On Saturday, Lithuania's state-owned railroad warned clients that regulated items, such as steel and iron would no longer be able to cross the country.

Similar restrictions will be applied on July 10 for concrete and alcoholic beverages, on August 10 for coal, and in December, no Russian oil will be allowed to enter EU territory.

Anton Alikhanov, the governor of the Russian exclave, estimates that the embargo will affect approximately fifty percent of all rail-bound products destined for Kaliningrad.