European Council president Donald Tusk has said 14 member nations have expelled Russian diplomatic staff over the poisoning of an ex-spy in the UK.
Mr Tusk said that there may be additional measures including further expulsions in the coming days and weeks.
In coordinated announcements of expulsions on Monday, the Czech Republic said it is removing three staffers from the Russian embassy over the poisoning of former double agent Sergei Skripal and his daughter Yulia (pictured below).
The Netherlands said it is expelling two Russian intelligence officers, while Estonia said it was expelling the Russian defence attache. The Italian Foreign Ministry announced that Italy would expel two Russian diplomats assigned to the embassy within a week.
Poland, Germany and Lithuania earlier confirmed they were among the European countries set to expel Russian diplomats.
Germany and Poland both said they had asked four Russian diplomats to leave, while in Lithuania, three Russian diplomats were ordered to leave.
The German foreign ministry said in a statement that the move was part of a joint European response to the Skripal case.
The expulsion of four diplomats is a strong signal of solidarity with Great Britain and signals the resolve of the Germany government not to leave attacks against our closest partners and allies unanswered.
The ministry added that the move was also a response to the recent cyber-attacks against German government networks, "which according to information so far is highly likely to be attributable to Russian sources".
The United States is kicking out 60 Russian diplomats and closing Russia's consulate in Seattle in response to the poisoning of an ex-spy in the UK.
Senior Trump administration officials said the expelled Russians include 12 spies who the US believes are working under diplomatic cover at Russia's mission to the United Nations.
They said the Seattle consulate is a counter-intelligence concern because of its proximity to a US Navy base.
Officials added that the actions are being taken to send a message about the "unacceptably high" number of Russian spies in the US and to respond to the attack in the UK.
The expelled Russians will have seven days to leave the US.
White House spokeswoman Sarah Huckabee Sanders said the actions would make the US safer by "reducing Russia's ability to spy on Americans and to conduct covert operations" that threaten national security.
"With these steps, the United States and our allies and partners make clear to Russia that its actions have consequences," Ms Sanders said.
Former Russian double agent Sergei Skripal and his daughter, Yulia, remain in a critical condition after they were poisoned with the highly lethal nerve agent Novichok in Salisbury on March 4.
The expulsions are one of the most significant actions US president Donald Trump has taken to date against Moscow and Russian president Vladimir Putin.
Less than a week ago, Mr Trump congratulated Mr Putin by phone for his re-election, but did not raise the spy case, renewing questions about whether the US president is too soft on the Kremlin.