The new trend/fashion in the West is to expell diplomats for no clear reason. 27 countries have now expelled Russian diplomats because they suspect Russia may have poisoned 2 citizens in the UK. However, while referring to the case, UK officials have always used the word "likely", in other words, it is just their supposition. No evidence has been showed. No standard legal procedure for this cases has been activated on the international level. In fact, no news about the health contitions of the two alleged poisoned persons have been reported any more. No word about Russia's motive to do something like that just before their elections and their hosting of the World footbal cup. The situation is foggy to say the least.
Russian Foreign Minister Sergei Lavrov has declared:
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,
These are the countries who has refused to expell Russian diplomats:
https://news.sky.com/story/salisbury-nerve-agent-attack-which-countries-are-not-expelling-russian-diplomats-11306512they can't just not react at all, but russia to can't react when former citizens give valuable information or denounce russia from abroad.