Seven former Soviet bloc countries have announced they are expelling Russian diplomats and Moscow is retaliating, in a series of disputes that are spiralling by the day. Here is an overview:
Czech authorities said on April 17 they were expelling 18 Russian diplomats whom they identified as spies. A day later Moscow expelled 20 Czech diplomats, giving them 24 hours to leave Russia.
Prague accuses Russian intelligence of being behind a deadly blast at an ammunitions depot in 2014. Russia dismisses the accusations as absurd.
The dispute escalated further on April 22 when Prague ordered Russia to remove most of its remaining diplomatic staff from Prague, prompting Moscow to demand a further cut in Czech embassy staff.
The two suspects named by Prague in connection with the 2014 ammunition depot explosion, known under the aliases Ruslan Boshirov and Alexander Petrov, have been reported to be part of the elite Unit 29155 of Russia's GRU military intelligence service.
Britain charged the pair in absentia with attempted murder after the poisoning of former Russian spy Sergei Skripal and his daughter with the nerve agent Novichok in the English city of Salisbury in 2018. Russia denied involvement in that incident.
Slovakia expelled three Russian diplomats on April 22, giving them a week to leave. It said it had acted in solidarity with the Czech Republic. Moscow has yet to announce counter-measures, but said it would do so soon.
"We are deeply disappointed by the unfriendly actions of Bratislava, which has decided to demonstrate pseudo solidarity with Prague on a trumped-up case," Russian Foreign Ministry spokeswoman Maria Zakharova said.
Warsaw expelled three Russian diplomats on April 15, saying that they had violated their diplomatic status and were involved in "activities to the detriment" of Poland.
Moscow said it would expel five Polish diplomats in response, giving them until May 15 to leave Russia. It said Warsaw's pretext for expelling Russian diplomatic staff was "absurd" and accused Poland of destroying bilateral ties.
Russia declared two Bulgarian diplomats "persona non grata" on April 20 in response to Sofia's expulsion of two Russian diplomats in March for suspected espionage.
Bulgaria threw out the Russian diplomats after prosecutors charged six people, including current and former military intelligence officers, with spying for Moscow.
LITHUANIA, LATVIA AND ESTONIA
The three Baltic states, all part of the Soviet Union until 1991, said on April 23 they were removing a total of four Russian diplomats.
Lithuania is sending two diplomats home and Latvia and Estonia one each. Those expelled had used diplomatic cover for spying, Lithuanian foreign affairs minister Gabrielius Landsbergis said.