Lithuania bans transit of some goods through its territory from Russia to its exclave of Kaliningrad, following EU sanctions.
Banned goods include coal, metals, construction materials and advanced technology, accounting for around 50% of all goods that Kaliningrad imports.
Russia's foreign ministry demanded Lithuania immediately lift the ban, threatened to take steps to protect its national interests if transport links were not restored.
Lithuania claim it is simply implementing sanctions imposed by the EU, of which it is a member, according to Lithuania's foreign minister.
The EU's foreign policy chief backed the decision, stating that it was just enforcing EU sanctions and not acting independently.
Kaliningrad is a Russian exclave sandwiched between Poland and Lithuania. Home to about 430,000 people, it is cut off from the rest of Russia.
The governor of Kaliningrad, urged locals not to resort to panic buying and reassured them that goods will be transported by sea from St. Petersburg.
