Russia created a secret facility for training up young men and women to seduce Western diplomats and obtain compromising information.
In Kazan, east of Moscow, the KGB chose new spies from young and impoverished parts of Russia and taught them how to approach foreigners in public spaces, like clubs or even brothels, that were often teeming with surveillance equipment.
Many of the new agents were singers, dancers, actresses and teachers.
In Russia-controlled East Germany, the KGB-linked secret service there trained them in a syllabus of Marxism, spycraft and psychological manipulation, and called the agents their "Romeos".
Among the male spies, most were well-educated, well-dressed and had an attractive sense of humour.
Former Stasi officer and "Romeo" spy Gerhard Bayer explained: "More important to these women was the inner values of these men who made them think: 'Yes, I could share my life with him'."
In Bonn, a secretary working for the West German chancellor, spent 14 years passing on classified information to her lover.
Another secretary, working at the US embassy in the same city, passed on more than 1,500 top-secret documents in a 22-year timeframe, Mark Hollingsworth writes in his new book, Agents of Influence, according to the MailOnline.
It wasn't until they were both arrested and jailed on espionage charges that they discovered their boyrfriends worked for the East German intelligence service.
The KGB even targeted male opera singers for their secret projects, with one of the most effective in Russia being a singer named Konstantin Lapshin.
When he was active, he seduced a number of officials and diplomats working at the US embassy in Moscow, including an employee of the US ambassador General Walter Bedell Smith.
The compromising information, branded "Kompromat" in Russia, was often used to blackmail officials - who would be made to choose between having their private lives exposed or betraying their country.
One case was made public in 1968 when the British ambassador to Moscow was recalled to Westminster. He had confessed to falling in love with his maid, who was now blackmailing him to reveal state secrets.
In 1972, a similar operation forced a married Brit diplomat, codenamed Karev, to reveal names of MI6 officers after pretending to be pregnant with his child - and ready to spill the beans.
John Vassall, working at the British Embassy, was threatened with having his homosexuality exposed after being photographed half-naked in bed with a lover.
He returned to London and spied for the Soviets for seven years until his arrest in 1962.
