Paul Manafort with Trump senior adviser Stephen Miller Drew Angerer/Getty Images

Paul Manafort offered private briefings on the Trump campaign to a Russian oligarch in hopes of resolving a business dispute, a new report says.

The dispute erupted as the result of a failed 2008 business deal.

Manafort's representatives say the offer of private briefings never materialized.

Former Trump campaign chairman Paul Manafort offered private briefings about the campaign to Russian oligarch Oleg Deripaska in hopes of resolving a years-long business dispute, sources told Bloomberg on Wednesday.

The dispute stemmed from a failed business deal the two pursued in 2008 involving a Ukrainian TV company called Black Sea Cable, according to Bloomberg. Legal complaints filed by Deripaska's representatives in the Cayman Islands in 2014 said he gave Manafort $19 million to invest in the company, but the project fell through and Manafort all but disappeared without paying back Deripaska.

Deripaska's representatives were "openly" accusing Manafort of fraud and pledging to recover the money from him as recently as early 2016, according to the Associated Press. But they reportedly backed off the accusations shortly after Manafort joined the campaign in the spring.

Shortly after being named a campaign strategist in April, Manafort emailed his longtime employee Konstantin Kilimnik — a Russian-Ukrainian operative with suspected ties to Russian intelligence — asking: "How do we use to get whole?"

Three months later, he emailed again, this time about Deripaska: “If he needs private briefings we can accommodate,” Manafort wrote.

Scott Olson, a recently retired FBI agent who spent years in the bureau's counterintelligence division, said that offer would have been "a counterintelligence flag."

"By doing so, he shows not only a willingness to give out campaign information he received in confidence but also an intent to earn personal income by selling the briefings," Olson said. "The 'routine briefings' excuse is not convincing because he is providing campaign information in exchange for money he will pocket."

Spokespeople for both Manafort and Deripaska have insisted that the private briefings never actually materialized. But if he did offer privileged campaign information "in exchange for debt cancellation," Olson said, that would have raised several red flags for US intelligence officials.

"First, of course is his willingness to disclose confidential information for personal gain," he said. "Second, and of more concern, is debt cancellation is much harder to track than payment. Payments leave a paper trail, debt forgiveness does not. It's a very effective way to conceal transfer of value and is another CI flag."

More broadly, Manafort's apparent readiness to trade information for financial gain would have made it easy for Russian entities to infiltrate and influence the campaign, said CIA veteran Glenn Carle.

"Just through Manafort alone, the campaign and Trump were penetrated by Russian intelligence operations," Carle wrote in an email.

He pointed to Manafort's use of code-words like "black caviar" in the emails he sent to Kilimnik as an example of activity that was likely "illicit" or "intelligence-related" activity.

"The euphemisms serve to divert (so the Russians and Manafort thought…) electronic pick-up of key words in electronic conversations," Carle said. "A counter-intelligence program is more likely to be tuned to detect 'money' than 'caviar.'"

Manafort also would have been an easy target, said Naveed Jamali, an intelligence analyst who secretly reported to the FBI for four years while pretending to work for a Russian spy.

"In espionage, when it comes to asset recruitment there are four pillars that motivate spies," he said. "Money, ideology, coercion and ego."

Jamali said that because Manafort was not paid for his work on the Trump campaign and has a history of doing business with international strongmen, financial incentives would have been "the perfect motivator."

The New York Times reported earlier this year that Manafort was in debt to pro-Russian interests by as much as $17 million by the time he joined the campaign.

Manafort of Republican presidential nominee Trump's staff listens during a round table discussion on security at Trump Tower in the Manhattan borough of New York Thomson Reuters

'Truly shocking'

White House special counsel Ty Cobb told Bloomberg shortly after news broke of the proposal of private briefings that "it would be truly shocking if he [Manafort] tried to monetize his relationship with the president."

Former Trump campaign manager Corey Lewandowski went as far as to say that Manafort "should go to jail" for the rest of his life if he colluded with Russia.

But Manafort's allies have pushed back strongly on the idea that he would have worked with a foreign government to help President Donald Trump win.

"Paul Manafort is a patriot. He would never work with any foreign power to tilt an American election," said Michael Caputo, a Trump campaign aide and friend of both Manafort and longtime Trump adviser Roger Stone.

"Anyway, he was busy cleaning up the profoundly amateurish mess Corey [Lewandowski] made of that campaign, saving the candidate from imminent doom — a full time-plus job even for a global election expert like Paul," Caputo said.

But Manafort did not necessarily need to be savvy to the Russians' intelligence efforts in order to abet them, said Carle, the former CIA official.

"This is how it is done," Carle wrote. "Approach someone with access and influence; propose benign-seeming justifications, offer an enticement, get benign-seeming favors done by the target in exchange (i.e., a meeting, a briefing, information that seems non-alarming), and use the meeting to feed information and shape events — either without informing the target (in this case, Manafort) or directly with his knowledge."

Deripaska and Manafort had worked together before the Black Sea Cable debacle. Deripaska signed a $10 million annual contract with Manafort in 2006, according to The Associated Press, for a lobbying project in the US that Manafort said would "greatly benefit the Putin Government." And In 2008, the pair looked into buying New York City's Drake Hotel and turning it into a luxury apartment building, The Daily Beast reported in August.

The Russia-related episodes that coincided with Manafort's accession to campaign chairman did not end with Deripaska or Kilimnik.

U.S. President Donald Trump listens to a question during a joint news conference with Colombia's President Juan Manuel Santos (not pictured) at the White House in Washington, U.S. Kevin Lamarque/Reuters A change in the GOP's Ukraine platform at the Republican National Convention, the release of hacked Democratic National Committee emails, and an early foreign policy adviser's trip to Moscow were apparently enough to raise red flags at the FBI, which had already begun to catch wind by the summer of 2016 that Russia was trying to influence the election.

Those factors, combined with Manafort's prominent campaign role and history of working with Ukrainian and Russia-linked entities, apparently spurred the bureau to seek a FISA (Foreign Intelligence Surveillance Act) warrant to surveil him.

Manafort stepped down shortly after The New York Times reported that the pro-Russia political party he had worked for had earmarked him $12.7 million for his work between 2007 and 2012. Ukrainian prosecutors have said they've found no proof of illicit payments to Manafort, who has said he never collected the payments.