The Czech Republic has warned Moscow that it will expel more Russian diplomats unless Czech Embassy staff ejected from Russia are allowed to return to work by noon on April 22.
In a dispute over Russia's alleged role in a deadly 2014 explosion at a Czech arms depot, 18 Russian diplomats identified by Czech intelligence as being intelligence operatives left their posts in Prague on April 19 as 20 Czech Embassy employees in Moscow also were forced to leave.
The tit-for-tat moves over the Czech allegations have triggered Prague's biggest dispute with Russia since the 1989 end of Communist rule, putting the small Central European NATO member at the center of rising tensions between Moscow and the West.
Foreign Minister Jakub Kulhanek told reporters on April 21 that Russia "has until 12 p.m. tomorrow to allow the return of all expelled diplomats back to the Czech Embassy in Moscow."
"If they cannot return, I will cut the number of Russian Embassy staff in Prague so it would correspond to the current situation at the Czech Embassy in Moscow," said Kulhanek, who was appointed as minister on April 21.
Russian Foreign Ministry spokeswoman Maria Zakharova said Prague should "leave ultimatums for communication within NATO."
"With Russia such a tone is unacceptable," she said, adding that the Czech ambassador would be summoned on April 22.
The Kremlin has rejected Prague's "baseless accusations" and called the Czech moves "unreasonable and harmful to bilateral relations."
Speaking after summoning the Russian ambassador in Prague, Kulhanek said Moscow's "disproportionate" retaliation "paralyzed the functioning of our embassy," while the expulsion of 18 Russian diplomats "did not jeopardize the functioning of the Russian Embassy."
The Czech Foreign Ministry put the number of Czech diplomats in Moscow at five, plus 19 other staff, after the expulsions. Russia's Embassy in Prague now has 27 diplomats and 67 other staff, according to the ministry. Both countries have additional staff at consulates in other cities.
As the spat escalates, the Czech government has decided to eliminate Russia's state-run corporation Rosatom from a multibillion-dollar tender to build a new unit at the Dukovany nuclear power plant.
Interior Minister Jan Hamacek, who was standing in as foreign minister until Kulhanek's appointment, has said that Prague would also no longer consider buying Russia's Sputnik V vaccine against COVID-19.
Citing Czech intelligence, the government said that Russia's military intelligence agency, the GRU, orchestrated the explosion in the eastern town of Vrbetice in 2014 in what the Foreign Ministry called "an unacceptable violation of the state sovereignty and national security of the Czech Republic."
The blast in October 2014 set off 50 metric tons of stored ammunition, killing two people. Two months later, another explosion of 13 tons of ammunition occurred at the same site.
In connection with the October blast, Czech police said they were seeking two suspected Russian agents also identified as suspects in the 2018 poisoning of former Russian double agent Sergei Skripal in England.
However, the open-source investigation organization Bellingcat said the Russian operation that Czech authorities have linked to the blast in Vrbetice involved at least six GRU operatives.
Prague has called on fellow European Union and NATO members to show "solidarity" by also expelling Russian diplomats.
EU foreign-policy chief Josep Borrell said in a statement on April 21 that the bloc "expresses full solidarity with the Czech Republic, supports the actions taken by its authorities so far, and stands ready to support its further efforts to bring those responsible to justice."
"The EU condemns the disproportionate reaction and subsequent threats of Russian Federation towards the Czech Republic," Borrell added. "Disruptive actions of Russian intelligence services against the interests and security of the EU and its member states will continue to be met with the staunchest resolve, including at the level of the European Union, as appropriate."
A NATO official has said that the allies "stand in solidarity over Russia's dangerous pattern of destabilizing behavior."
Skripal, a former Russian military intelligence officer, and his daughter Yulia nearly died after being exposed to what British authorities later concluded was Novichok, a military-grade nerve agent. A British woman who accidentally came into contact with the substance died.
Britain's NATO allies responded to the Skripal poisoning by imposing sanctions on Russia and expelling diplomats.