Donald Trump was likely to have been compromised by Russian intelligence agents on a trip to Moscow 31 years ago, a new book claims.
Trump had been officially invited to Russia by a senior diplomat to discuss possible property developments.
However, during his stay, Trump would have been filmed in 1987 with Russian prostitutes sent to him as a "honey trap", even though he travelled with then-wife Ivana, making him vulnerable to blackmail by the Kremlin, its then top spy told the book's author.
The material would have been carefully conserved by spies since then, according to the Daily Mail.
Oleg Kalugin, the former head of counterintelligence for the KGB, told author Craig Unger that Trump would have had "many young ladies at his disposal" - and Russia would have been watching.
Kalugin claimed that Trump probably even knows about the existence of the files about him containing material the Russians call "kompromat".
The extraordinary claim is in House of Trump, House of Putin; the Untold Story of Donald Trump and the Russian Mafia, a forensic look at Trump's long ties to Russia, which is out next week, and written by Unger.
The author, a Vanity Fair journalist, previously targeted the Bush family over alleged links to the Saudis, and was heavily quoted in Michael Moore's Fahrenheit 9/11 movie.
The book, a copy of which has been obtained by DailyMail.com, claims that Trump is a "Russian asset" whose greed made him "easy prey" to Soviet intelligence officers decades ago.
It has no direct evidence of the existence of such tapes, however.
House of Trump also details how two Trump associates who in 2013 went to a party held by a notorious Russian criminal overlord and talked about "getting together with Vova" - meaning Vladimir Putin.
Speculation about Trump's ties to Russia and possible collusion with the Kremlin in the 2016 election that saw him elected US President has reached fever pitch as the investigation by Special Counsel Robert Mueller into meddling in the vote gathers steam.
While Mueller has already indicted 32 people and three Russian companies, the Russia involvement all relates to hacking, which US intelligence agencies have concluded definitely did take place.
Despite this, Trump has been soft on Russia, Unger says, and at his summit with Putin in Helsinki last month shocked the world by saying that the Kremlin did not conduct any meddling.
In a devastating opening chapter to his book, author Unger says that the reason is simple: with Trump, Russia "implanted either a willfully ignorant or an inexplicably unaware Russian asset in the White House".
Unger calls Trump "Vladimir Putin's man in the White House" and claims that Trump's real estate business, The Trump Organization, has likely laundered billions for organised crime in Russia.
The White House directed DailyMail.com to the president's personal attorneys.
A lawyer for the president was not immediately available to comment on Trump's alleged conduct, as detailed in Unger's book.
House of Trump says that Trump's associations with shady Russians dates back to the 1970s in Brighton Beach, a working-class neighbourhood in Brooklyn where his father Fred owned dozens of properties.
Among them were Semon Kislin and Tamir Sapir, Russian emigres who supposedly had ties to Russian crime families and started an electronics store which was used by KGB agents to buy their supplies.
Another was David Bogatin, a Russian-born Soviet Army veteran turned US citizen who later pleaded guilty to running a gasoline bootlegging scheme with Russian mobsters.
Trump had no problem with Bogatin buying five luxury condos in Trump Tower, his brand new apartment block on Fifth Avenue in New York, in the mid-1980s for US$6 million.
Although that is the equivalent of US$14.5m today when adjusted for inflation, property prices in New York have far outstripped regular inflation, making the equivalent price today far higher than that.
In fact, Trump Tower was one of only two buildings in New York at the time that allowed people to buy condos using shell companies which disguised who the buyer was.
House of Trump says that whether Trump knew it or not, when he closed the deal with Bogatin he had "just helped launder money for the Russian mafia".
Trump had ambitions beyond New York and when he began to take control of the family business he looked abroad - and found willing partners in what is now Russia.
In January 1987, two years before the fall of the Berlin Wall, he was invited by the Soviet ambassador to the United Nations, Yuri Dubinin, to visit Moscow to talk about opening a new hotel there.
Trump flew with his first wife Ivana and two unnamed associates to what was then Soviet Russia.
He stayed at the National Hotel in Moscow and during his entire trip was almost certainly under 24-hour surveillance by the KGB.
Kalugin, who headed the KGB's branch of the First Chief Directorate, which was responsible for foreign operations and intelligence gathering, said that it was widespread practice at the time to use prostitutes to entrap foreign businessmen.
"In your world, many times, you ask your young men to stand up and proudly serve their country," Kalugin once told a reporter. "In Russia, sometimes we ask our women just to lie down."
In an interview for House of Trump Kalugin – who was one of the KGB's most senior officers at a time that Putin was a more junior officer - said that Trump would probably have "had many young ladies at his disposal".
He said: "I would not be surprised if the Russians have, and Trump knows about them, files on him during his trip to Russia and his involvement with meeting young ladies that were controlled [by Soviet intelligence]."
The trip was long before Trump's 2013 visit to Moscow to attend the Miss Universe pageant. It was that visit which led to allegations that he was filmed watching prostitutes urinate on a bed once used by Barack and Michelle Obama – claims he has denied as false and "fake news", but which have led to the notorious "golden showers" dossier.
The claim was first made in the dossier prepared for former British spy Christopher Steele, who was commissioned during Trump's election campaign by Fusion GPS, a Washington "research firm" to look into his Russian ties.
Fusion GPS was commissioned in turn, first by the conservative-leaning Washington Beacon and then by lawyers for Hillary Clinton's campaign, to dig up dirt on the Republican candidate. The Free Beacon says Steele was not commissioned by them and that he was used by Fusion GPS after the Free Beacon's involvement had ended.
Trump's ties to Russia deepened in the 1990s after his casinos in Atlantic City began to go bankrupt and his companies went into US$3.4 billion of debt.
Unable to get cash from banks in the US Trump went to Russians to get what is known as "alternative financing", Unger writes.
As Propublica have reported, this involved Trump using money from wealthy Russians to buy half of the new condos in his new apartment blocks so that he could get financing for the rest.
During the late 1990s around 20 per cent of Trump branded condos, or 1300 luxury properties, were sold to anonymous shell companies, the equivalent of US$1.5b in value.
Around this time Bayrock Group LLC entered Trump's world courtesy of Tamir Sapir, the Russian emigre who knew Trump from his Brighton Beach days and by now had become a billionaire.
Bayrock was a real estate company that Unger describes as "largely staffed, owned and financed by emigres from Russia and the former Soviet Union".
Bayrock's leadership were even more dubious and were a "cozy family of billionaire oligarchs from the former Soviet Union".
Trump apparently had no problem with this and Bayrock moved into Trump Tower and set up office on the 24th floor. Trump's office was on the 26th.
Unger says that it is "murky" where it got its funding but with Bayrock's help - and his appearance on the The Apprentice - Trump was back.
Trump signed deals to license his name to an 813-unit development called Trump Towers in Sunny Isles Beach, Florida and a 35-story tower in White Plains, New York, among other projects.
Bayrock was involved in Trump SoHo,
But "House of Trump" suggests that Bayrock had an ulterior motive and was little more than a modern day version of the old KGB trick of creating a shell company that would launder Russian money and gather intelligence on Western targets.
In Trump's case, the future president was "indirectly providing Putin with a regular flow of intelligence on what the oligarchs were doing with their money in the US", Unger writes.
He quotes federal prosecutor Kenneth McCallion who previously pursued Ukrainian oligarch Dmitry Firtash, Trump's former campaign manager Paul Manafort and notorious Russian mobster Semion Mogilevich.
McCallion said: "I believe that Christopher Steele was right.
"Initially, Trump wasn't that important to Putin. But now that Trump was getting investments from the Russians, Putin could keep track of where their money went because Bayrock kept a ledger that Moscow likely had access to.
"It was not just about buying condos, which was the tail wagging the dog. It was direct capital investment into Trump projects.
"Putin didn't stop the expatriation of billions of dollars because he benefited from it, but it was a serious problem for the Russian economy. Billions of dollars were going out and he really wanted to keep track of it for a variety of reasons, to see what the financial strength was of the oligarchs."
"House of Trump" says that In February 2013 two Trump associates turned up at the 55th birthday of Sergei Mikhailov, who is thought to be the leader of the Russian Solntsevo crime gang.
The event took place at the Radisson Royal in Moscow and to celebrate Mogilevich, the crime overlord, had taken over an entire floor.
The two associates of Trump claimed they were there to talk about putative Trump Towers in Moscow and Kazakhstan, possibly with Solntsevo as a partner.
A source said that the Americans talked about a meeting they had with Ivanka Trump, Trump's daughter. They also talked about "getting together with Vova", meaning meeting up with Putin.
Unger writes: "The Americans, the source said, were not introduced to everyone by name.
"One of them, however, was described as being five foot eight or nine, heavyset, with curly hair and a receding hairline, 'definitely not slim, and having a California smile."
"Later, the source thought that he was likely Felix Sater, 'because (he) saw his pictures".
Sater is a Soviet-born former adviser to Trump, a convicted felon and onetime stock scammer who is at the center of the Trump Russia nexis - he was also managing director of Bayrock.
During the 2010s Trump's connections to Russia and his reliance on Russian money appeared to deepen.
In a 2104 interview with Trump's son Eric, who was by then helping to run The Trump Organization, golf writer James Dodson claimed that he admitted this was the case.
Dodson said that Eric Trump told him: "Well, we don't rely on American banks. We have all the funding we need out of Russia".
Dodson replied: 'Really?' and Eric Trump said: "Oh, yeah. We've got some guys that really, really love golf, and they're really invested in our programs. We just go there all the time."
Eric Trump also supposedly said that they had "access to US$100 million" for their newest golf course in North Carolina.
Eric Trump denied the conversation had taken place and said in 2017: "This story is completely fabricated and just another example of why there is such a deep distrust of the media in our country #FakeNews." Dodson, however, stands by his account.
Before, during and after the 2016 election Trump has furiously denied that he worked with Russia to get elected and in dozens of tweets has said there is "No Collusion!"
The President sees it as an affront to his ego that the Russians could have helped him beat Hillary Clinton and is unable to separate the Kremlin's meddling from his victory, the book says.
The most serious of Trump's campaign troubles has become the notorious meeting at Trump Tower in 2016 in which Russians with ties to the Kremlin offered him 'dirt' on Hillary Clinton.
The meeting was attended by Trump Jr, the President's son-in-law Jared Kushner, his former campaign manager Paul Manafort and a Russian lawyer.
Trump long denied that he knew about the meeting in advance but in a recent Tweet he admitted its true purpose.
The President wrote: "This was a meeting to get information on an opponent, totally legal and done all the time in politics - and it went nowhere. I did not know about it!"
Trump has now reportedly been told to stop tweeting about the meeting by his lawyers who feel it is harming him and adding oxygen to the interest in what took place.
Another link to Russia is that the Robert Mueller Special Counsel's investigation was begun after Trump's Attorney General, Jeff Sessions, recused himself from leading it, saying it was because of his involvement in the Trump campaign.
Unger accuses him of actually stepping back because he lied to Congress about his meetings with the Russian ambassador to the US - although Sessions denies that charge.
And then there is Manafort who made US$60 million from political consultancy work for pro-Putin politicians in Ukraine, and who is currently on trial charged with bank and tax fraud.
When that trial is over he will stand a second trial in which the charges will include conspiracy against the United States.