Twenty-six countries around the world, including the United States, have announced plans to toss out Russian diplomats in an unusually coordinated response to a nerve-agent attack in Salisbury, England, that targeted a Russian ex-spy and his daughter.
Affecting at least 150 people, it is the largest expulsion of Russian diplomats since the Cold War - and virtually unprecedented in scale and scope.
In Europe, even countries that normally pursue Russia-friendly policies, such as Hungary and Italy, joined the action as a sign of solidarity with Britain, a marker of just how disturbing they found the attack on Sergei Skripal and his daughter, Yulia.
Britain has pinned the blame squarely on the Russian Government. Most countries said they were expelling diplomats they believed were actually undercover intelligence agents.
Belgium, Ireland, Moldova and Australia were the latest to join the list of countries taking measures against Russians, and Nato also said it was kicking out seven diplomats from the Russian mission to the alliance.
"This sends a clear message to Russia that there are costs and consequences for its unacceptable and dangerous pattern of behaviour," said Nato Secretary-General Jens Stoltenberg as he announced the expulsions. "And it follows Russia's lack of constructive response to what happened in Salisbury."
Russian leaders have said they will respond to the expulsions, although they have not announced specific plans.
"We know for certain that this is the result of colossal pressure and colossal blackmail that, regrettably, is Washington's main instrument in the international arena today," Russian Foreign Minister Sergey Lavrov told reporters in Uzbekistan, Interfax reported.
Apart from Britain, which will kick out 23 diplomats, and the United States, which is expelling 60, most of the countries have opted for one or two, a symbolic move that is unlikely to significantly disrupt Russian intelligence activities.
European policymakers acknowledged the expulsions were limited in each of their countries, but they said the international sweep would force Russian intelligence services to think twice before conducting similar attacks.
"The symbolism is the best way to serve a real, functional message to the leadership of Russia," said a former head of a European intelligence service.
In other cases when the Kremlin has allegedly conducted covert attacks on Western soil, governments have often floundered about how to respond if they cannot prove Russian culpability with absolute certainty, the official said. But that only emboldens the Kremlin.
"It's a huge dilemma for heads of state to decide how to respond," the official said. "And for a long time, the response was too soft and seen as a sign of weakness."
Here's the full list so far:
United States: 60
Czech Republic: 3
The Netherlands: 2