Russian intelligence uses the name to differentiate such officers from “legal” spies who are posing undercover as diplomats. Many countries use spies pretending to be ordinary people but Russia has long specialised in a type of deep-cover illegal agent who takes on an entirely different nationality. These spies pretend to be American, British, Canadian or – in the case of Ferreira – Brazilian to allow them to move in circles where Russians would be met with suspicion and therefore find it harder to operate.
