The book's author said Trump became a target for the Russians in 1977 when he married his first wife, the Czech model Ivana Zelnickova.
"He was an asset. It was not this grand, ingenious plan that we're going to develop this guy and 40 years later he'll be president," Unger told The Guardian.
Unger added: "Trump was the perfect target in a lot of ways: his vanity, narcissism made him a natural target to recruit. He was cultivated over a 40-year period, right up through his election."
Trump's 1987 book, "The Art of the Deal," described a visit to Moscow to discuss building "a large luxury hotel across the street from the Kremlin in partnership with the Soviet government."
In fact, Shvets said, Russian operatives used the trip to flatter Trump and told him he should go into politics. Shvets told The Guardian that KGB operatives were then stunned to discover that Trump had returned to the United States, mulled a run for office, and taken out a full-page ad in several newspapers that echoed anti-Western Russian talking points.
The ad, which ran in The Washington Post, The New York Times, and The Boston Globe, was titled "There's nothing wrong with America's Foreign Defense Policy that a little backbone can't cure."
The ad accused Japan and other countries of "taking advantage" of the United States and said the US should stop paying to defend other rich countries — arguments that would become the backbone of his foreign policy when he became president decades later.
Shvets said the ad was considered an "unprecedented" success in Russia's attempts to promote anti-Western talking points in American media.