Russia has summoned the European Union’s envoy to Moscow to “strongly” protest new restrictions on goods shipments to its Kaliningrad exclave through EU member Lithuania while threatening the Baltic state with “retaliation.”

The Foreign Ministry in Moscow said on Tuesday that EU Ambassador to Moscow Markus Ederer was informed of the “inadmissibility of such actions” and warned “retaliation will follow” if the restrictions aren’t removed immediately. It did not elaborate.

Kaliningrad is wedged between Lithuania and Poland, where the Pregolya River feeds into the Baltic Sea. It has about 500,000 inhabitants.

Lithuanian officials said they imposed the restrictions beginning on June 20 in an effort to shore up punitive measures that followed Russia’s ongoing invasion of Ukraine on February 24.

Ederer echoed that line after the meeting in Moscow, saying that “Lithuania is not taking unilateral measures, it is implementing EU sanctions.”

He added that there was no blockade of Kaliningrad as the transit of non-sanctioned goods to the enclave continues.

The Kremlin, meanwhile, dispatched one of President Vladimir Putin’s top allies to Kaliningrad, where he warned that “appropriate measures” will be taken by Moscow “in the near future.”

“Russia will certainly respond to such hostile actions,” Russian Security Council chief Nikolai Patrushev said at a regional security meeting in Kaliningrad.

“Their consequences will have a serious negative impact on the population of Lithuania,” he warned.

Some information came from Reuters, AFP, and AP.