There is a war going on in Europe.
More than 400 Russian diplomatic staff have been kicked out of embassies and diplomatic missions across Europe since the beginning of March.
The majority of those expelled are suspected of being Russian intelligence operatives.
There have been major expulsions of diplomatic staff. The European countries expelled nearly 200 Russians after the attempted assassination of Sergei Skripal in the UK.
This wave of expulsions may be the biggest since the fall of the Soviet Union.
The current wave is notable for the number of countries expelling Russians and for the number of countries expelling the EU itself.
Chris Miller, a professor at the Fletcher School of Law and Diplomacy, called the expulsions a long-awaited response to Russia's security services in Europe.
For too long, many European governments have given them a free hand, even though Russian agents have been implicated in assassinations and attacks from Berlin to London.
Austria, Bulgaria, and Germany have good relations with Moscow, which is one of the reasons why they are expelling Russians. The Russian ambassador to Lithuania was one of the legitimate diplomats who were expelled.
The majority of those expelled were suspected of being intelligence operatives or diplomats in violation of the Vienna Convention on Diplomatic Relations.
Poland expelled 45 Russian diplomats on March 23, which was justified by a spokesman for the country's intelligence chief, who said that Russia uses diplomacy not to remain in contact with partners but to push false claims and propaganda against the West.
Pushing false claims has been a staple of Russian activity in Europe for decades. Moscow wants to promote its interests and erode trust in foreign governments.
Russian agents in a target country increase the reach of misinformation by working with locals.
In the French presidential and German federal elections, Russian interference was found in calls for Catalonia to break away from Spain. Russia is suspected of trying to undermine the EU by meddled in the 2016 vote for the UK to leave the EU.
NATO and the EU are targets of Russian espionage. NATO expelled intelligence agents from Russia in October. Russia stopped its mission.
Russian espionage has targeted military and space-related technology in Europe. Russian operatives are suspected of carrying out assassinations in Europe.
Two warehouses belonging to the arms company EMCO were bombed in the Czech Republic. Two Russians with the GRU were suspected of being involved in the attack on EMCO.
A high-ranking GRU officer was in Bulgaria a year later when the owner and two others of EMCO were poisoned. Three people survived. The attempted assassination of Skripal and his daughter in the UK was carried out by the same officer.
Russian agents assassinated a Chechen dissident in Berlin.
The fight against Russian espionage has spread across Europe, but it is more concentrated in a few areas.
The number of international organizations in Vienna and Brussels allow Moscow to assign more operatives as diplomats in Belgium and Austria.
The problem has been made worse by some governments.
Miller told Insider that the Austrian and Hungarian governments are notorious for their open-door attitude toward Russian agents. Hungary, which has good relations with Moscow, has not expelled Russians during this wave of expulsions.
The Joint Intelligence and Security Division was created by NATO in response to Russia's malign activity. The alliance wanted to increase its intelligence and counter-intelligence capabilities. The unit was strengthened by NATO in 2020.
The intelligence presence in Russia's diplomatic outposts in Europe was found to be packed with Russian agents after a NATO audit.
Russia sent home diplomats from European countries and the EU in response to the recent expulsions. Russia's deputy foreign minister said this month that Moscow was still assessing the expulsions of its personnel, but that they advocated for diplomatic channels to remain open.
Miller said the expulsions by European countries were a good step, but after three decades of giving Russian agents free reign across the continent, there is much more that needs to be done.
Constantine Atlamazoglou works on security. He obtained a masters degree in security studies and European affairs from the school.