Europe has kicked out around 400 Russian diplomats since 2022 and caught at least 15 suspected spies. Some of these spies are rumored to be "ghosts" – agents using fake identities of deceased people.

In August 2023, Britain shocked its neighbors by charging three Bulgarians with spying for Moscow. These seemingly ordinary people were allegedly hiding fake passports and building secret networks in the suburbs. “It is a bit freaky,” said a barber from northwest London.

While tabloids sensat...