A senior Russian diplomat has warned that Moscow might rupture diplomatic relations with Washington if the United States designates Russia a state sponsor of terrorism, the latest in a range of diplomatic sparring in recent days between the Kremlin and capitals that support Kyiv.

A terrorist designation would cause “the most serious collateral damage to bilateral diplomatic relations,” Alexander Darchiev, the director of the Russian Foreign Ministry’s department for North America, told the official news agency TASS in a brief interview published on Saturday.

It could result in lowering or breaking off ties entirely, he said, adding, “The U.S. side has been warned.”

The Kremlin was also sharply critical of recent calls by Western nations to bar all visitors from Russia, including students, tourists and business executives. Dmitri Peskov, the presidential spokesman in Russia, said such attempts to isolate Russia were bound to fail.

Both issues have been pressed by President Volodymyr Zelenskyy of Ukraine.

The Czech Republic, Estonia, Latvia and Lithuania have said that they will stop issuing tourist visas to Russians. Estonia and Finland called for a collective European Union ban, but other nations rejected the idea, with Germany saying that such a move would harm “innocent people.”

Russians who fled abroad to escape the Kremlin’s draconian measures to imprison critics of the war, as well as President Vladimir Putin’s increased repression generally, have also been critical. Tens of thousands of Russians are trying to establish new lives abroad, and some of the most outspoken would face jail if they were forced to return to Russia.