Congressional investigators looking into President Trump’s ties to Russia are scheduled to hear Friday from one of the most cooperative Trump associates yet: Felix Sater, a Russian-born real estate developer who said he plans to discuss previously undisclosed details about his efforts to get a Trump tower built in Moscow.

While the testimony of former Trump aides has been largely stymied so far by White House objections, Sater, who has a long history of assisting government investigations, said he plans to give substantive answers during his closed-door interview with the House Intelligence Committee.

“I will answer every question without exception,” said Sater, who worked on two separate efforts to develop a Trump tower in Russia. “I always have and always will cooperate with anything the U.S. government asks of me.”

Among the topics Sater said he plans to address: How a former Soviet army general offered him advice on developing a Trump tower project in Moscow during the 2016 campaign — interactions that were not detailed in former special counsel Robert S. Mueller III’s report.

Sater is also expected to provide additional details about how he and Michael Cohen, then Trump’s personal attorney, pursued the deal even as Trump was seeking the Republican presidential nomination. Cohen, who is now serving a three-year prison sentence, admitted last year that he lied to Congress when he said that discussions about the project ended in January 2016.

An attorney for the Trump Organization declined to comment on Sater.

Trump has said he barely knows the onetime stockbroker, and skeptical GOP committee members note his criminal convictions for a 1991 assault and a Mafia-backed stock scheme in the late 1990s.

For his part, Sater is expected to offer — as a testament to his credibility — details about what he describes as a two-decade-long history of assisting the FBI, the CIA and Defense Intelligence Agency on highly sensitive investigations.

With new details about his life as a secret government operative, Sater brings even more drama — and another larger-than-life character — to the already baroque Russia story.

His work for the U.S. government, he claims, included helping track Osama bin Laden before and after the 9/11 attacks, locating Stinger missiles at risk of being sold to al-Qaeda and providing information about assassination plots against then-Secretary of State Colin L. Powell and President George W. Bush.

Some current and former law enforcement and intelligence officials familiar with the claims of the fast-talking entrepreneur who grew up on Surf Avenue in Brooklyn, in the shadow of the Coney Island amusement park, said he has exaggerated his role.

But according to several former prosecutors and government documents reviewed by The Washington Post, Sater made significant contributions as a government cooperator.

“He was extraordinarily valuable,” recalled Todd Kaminsky, a former federal prosecutor in the Eastern District of New York who represented the U.S. attorney’s office at Sater’s 2009 sentencing hearing and on other matters. “He had knowledge of so many different areas — from financial fraud to terrorism to street crime.”

Kaminsky said that both prosecutors and FBI agents spoke on Sater’s behalf at his 2009 sentencing, and that the letter the U.S. attorney’s office submitted detailing his cooperation “was unlike any I had seen as a prosecutor in its detail and breadth.’’

Justice Department veterans said that one of Sater’s most impressive assets was his far-flung networks of contacts — which include mob bosses in Queens, Afghan warlords and Ukrainian oligarchs.

Among his close associates is a retired Soviet army general named Evgeny Shmykov who Sater said aided his anti-terrorism inquiries in the 1990s and later helped him with the Trump Tower Moscow project. Shmykov, reached by telephone in Moscow, confirmed Sater’s account.

Among FBI agents, Sater’s ability to leverage information and operational plans earned him the nickname “Quarterback.”

Sater jokingly embraces a different moniker, a nod to his Jewish heritage: “Moishe Bond.”

'Critical' cooperation

Sater was born in Moscow and moved to the United States at age 7 with his parents, who he said were fleeing anti-Semitism in the Soviet Union.

The family settled in Brighton Beach, where Russian emigres congregated in the 1970s. His father, Misha, was a former boxer and butcher turned cabdriver who could quote Chekhov and Tolstoy from memory.

At social events during their high school years, Sater met Michael Cohen, who would go on to be Trump’s longtime personal attorney.

After a year and a half at New York’s Pace University, Sater became a broker at Lehman Brothers — a career that was derailed after a Manhattan bar fight in 1991, when he stabbed another man with a margarita glass. He served a year in prison and lost his broker’s license.

He eventually went to Russia to pursue business deals to support his family, he said.

Sater, a U.S. citizen, said he first cooperated with the government while working in Moscow in the mid-1990s on telecom deals in the newly privatized Russian market. At a party, he said, he met a Defense Intelligence Agency employee working undercover in Russia who asked Sater to help gather information about a new Russian radar system.

DIA officials declined to comment.

Months later, Sater said, he learned that he was under investigation in the United States for his role in a stock fraud scheme run out of a Mafia-linked brokerage firm where he had worked just after getting out of prison.

Sater came back to New York, pleading guilty in 1998 to one count of racketeering as part of a $40 million stock fraud in which Wall Street brokers artificially inflated the price of stocks.

The scheme relied on members of the La Cosa Nostra crime families for extortion and to resolve disputes, federal authorities alleged, part of a concerted effort by organized crime to make inroads on Wall Street.

Sater was spared prison time, thanks to the information he provided on national security matters and his role in the conviction of several Mafia figures, according to court records and interviews with former officials. Kaminsky, the former prosecutor, told the court that while Sater’s criminal conduct was “serious and real, I don’t think there’s any question that Mr. Sater has prevented far more financial fraud than he has caused.”

Justice Department filings reviewed by The Post describe Sater taking personal risks to provide information about al-Qaeda’s financial structure, North Korea’s nuclear program and organized-crime leaders in Russia, among other matters, as BuzzFeed reported last year.

“Sater provided the United States intelligence community with highly sensitive information in an effort to help the government combat terrorists and rogue states,” according to a 2009 court filing.

The document noted that prosecutors could not confirm whether all of the information Sater provided checked out. “Sater, acting in good faith, simply made this intelligence available to those who were in a position to determine its value,” it read.

At Sater’s 2009 sentencing hearing, deputy U.S. attorney Marshall Miller lauded Sater’s efforts “to protect the United States. His cooperation was critical and he did go above and beyond what virtually any cooperator I have seen has done,” he said, according to a court transcript.

Miller declined to comment. The CIA, FBI and the Justice Department declined to comment.

Several current national security officials, speaking on the condition on anonymity to discuss sensitive matters, said Sater made numerous offers of information but disputed that he provided intelligence of value.

Sater and his attorney, Robert Wolf, said that Sater worked extensively with law enforcement and intelligence agencies and that both were told his information was helpful.

Gathering intelligence on al-Qaeda and the mob for the U.S. government provided him with a sense of purpose, Sater said.

“It gave me a feeling of redemption that I was making up for my past misdeeds,” he said.

His sources included several top former Russian military figures, Sater said, including Shmykov, who had worked in military intelligence, as the New York Times first reported.

After the collapse of the Soviet Union, Shmykov said he worked in the 1990s in a private capacity as an adviser to leaders of Afghanistan’s Northern Alliance, which was at odds with the Taliban and al-Qaeda.

Shmykov told The Post in the phone interview that he connected Sater with sources in Afghanistan and that the two traveled through the country together.

Shmykov said that it was clear that Sater’s loyalty was to the United States but that the two shared a common enemy — al-Qaeda and the Taliban.

“He did a lot for your country,” Shmykov said, adding: “There were attempts to get him to work for Russia, but this was pointless. There were personal relationships” in the United States.

Real estate partners

Around 2000, Sater sought to remake himself as a real estate developer. He co-founded a company called Bayrock Group and rented space on the 24th floor of Trump Tower, two floors below Trump’s own offices.

Shortly after moving in, Sater said he went upstairs to meet his new landlord. “I said, ‘Mr. Trump, I am going to be the biggest developer in New York, and I think you are going to want to be my partner.’ ”

Trump laughed, Sater said, and then called two Trump employees over and told Sater to talk with them about his ideas.

In the months following that introductory meeting, Sater said he pitched the idea of building Trump towers in cities across North America and around the world, including Istanbul, London, Moscow, Warsaw and Kiev, Ukraine.

Trump gave Bayrock rights to use his name in developments in Arizona, Florida and New York — and a one-year deal in 2005 to develop a project in the Russian capital, according to court filings obtained by The Post.

Sater traveled with Donald Trump Jr. to work on a proposed tower in Phoenix and with the future president to unveil a proposal for a Trump tower in Denver, he said.

All the while, Sater promoted himself as the leading developer of Trump properties, recalling that he told would-be investors: “I can build a Trump tower because of my relationship with Trump.”

In 2005, Sater said he found potential investors in Moscow and a possible site: a shuttered pencil factory that had been named for American radicals Nicola Sacco and Bartolomeo Vanzetti, who were convicted of murder and executed during the “Red Scare” that swept the United States after World War I.

He had architectural plans drawn up by a New York firm and reviewed the project closely with Trump, he said.

In a 2007 deposition, Trump acknowledged that Sater’s company, Bayrock, had brought Russian investors to his office to discuss building in Moscow. “It’s ridiculous that I wouldn’t be investing in Russia,” Trump said. “Russia is one of the hottest places in the world for investment.”

Sater also said he squired Ivanka Trump and Trump Jr. around Moscow at their father’s request, even arranging a private tour of the Kremlin for Ivanka Trump, who was invited to sit in President Vladi­mir Putin’s chair.

A spokesman for Ivanka Trump’s attorney declined to comment.

Alan Garten, an attorney for the Trump Organization, declined to comment on Sater’s relationship with Donald Trump. But in 2016, he told the The Post that Sater’s description differed from Trump’s.

“I can see how the relationship may have been viewed differently from one person’s side of the relationship from the other,” Garten said, adding: “There was no relationship with Mr. Sater. The relationship was a business relationship with Bayrock.”

In a deposition for a 2013 lawsuit, Trump said he interacted with Sater only occasionally, adding, “If he were sitting in the room right now, I really wouldn’t know what he looked like.”

In the end, the Moscow pencil factory project foundered. Bayrock ended up developing only two Trump-branded properties, in Fort Lauderdale, Fla., and in the SoHo neighborhood of New York.

During that period, Sater said he recalls talking with Trump “sometimes more than 20 times in a single week.” In 2010, the year the SoHo hotel opened, Sater moved into an office inside the Trump Organization’s 26th-floor suite — three doors down from Trump himself.

A lucrative proposition

When Trump announced his presidential bid in 2015, Sater saw a golden opportunity to push once again for a Trump tower in Moscow — while also elevating the New York businessman on the world stage.

“I want to get a tower built, and I am all excited,” Sater recalled thinking in 2015 as he contemplated connecting Trump and Putin during the campaign. “I am going to make $100 million on this deal.”

Sater acknowledges that his communication about the project during the campaign was entirely through Cohen. But he said that “every signal I got was that Trump loved this idea about pushing the Trump Moscow tower during the election campaign” as a way to boost Trump’s political and financial prospects simultaneously.

Cohen has said Sater approached him with a proposal for a Moscow project in September 2015. He had found a new Russian partner, a Moscow-based developer called I.C. Expert Investment Co., whose chairman was a former Sater business partner named Andrei Rozov.

In October, Trump signed a letter of intent to proceed with the Sater project, Cohen has said. It came on the same day Trump participated in the third Republican debate.

Cohen told Congress in February that Trump kept tabs on the project throughout the 2016 race.

“There were at least a half-dozen times between the Iowa caucus in January 2016 and the end of June when he would ask me, ‘How’s it going in Russia?’ — referring to the Moscow tower project,” Cohen testified before the House Oversight Committee.

While Cohen talked with Trump, Sater said he concentrated on Moscow, drawing on the advice of other powerful Russian friends during this period, including Shmykov, other former military officials and a top executive of GenBank, a Russian financial institution now based in Kiev.

In Moscow, Sater said he and Rozov circulated plans for a 100-story glass-and-steel Trump tower, designed in the shape of an obelisk, that was to be the tallest building in Europe, as BuzzFeed has reported.

In his interview with The Post, Shmykov confirmed Sater’s account of his role in the Trump Tower project.

“He turned to me with this project” and others, Shmykov said, saying he talked to Sater about the Moscow tower beginning in early 2015 and into 2016.

Shmykov said his role on the project was “as an adviser — a senior comrade,” helping Sater and Cohen with influential Russian contacts, including those who could help acquire land. His outreach included checking out a site for a proposed land deal in the Moscow suburb of Krasnogorsk.

Shmykov said that he also spoke to Cohen several times by phone but that he couldn’t remember whether the conversation was in 2015 or 2016.

A lawyer for Cohen, Lanny Davis, declined to comment.

Sater said Shmykov helped secure invitations and visas for Cohen and Trump to visit Russia in June 2016 — a trip that Cohen canceled as the Republican convention loomed.

Mueller’s report describes Sater’s efforts to secure the Moscow development, which it says could have been worth millions for Trump, but it does not mention Shmykov’s role in the unsuccessful effort.

“I was very disappointed” that the project stalled, Sater said. “I could have really used that $100 million — and I wouldn’t have minded being known as the guy who built the tallest structure in Europe.”

Sater said he continued his relationship with the FBI until 2016 but said he did not provide the bureau information related to Trump during the campaign. In 2017, Sater said he was contacted by the special counsel’s office. He said he cooperated with Mueller’s team fully, meeting twice with investigators and testifying once before the grand jury.

House Intelligence Committee Chairman Adam B. Schiff (D-Calif.) has said he believes Sater’s testimony before his panel can help illuminate Trump’s interest in Russian business opportunities.

“Our paramount interest is in the Trump tower Moscow project and what went into trying to make that deal happen,” Schiff said in an interview in March. “The idea that a president of the United States was seeking a multimillion-dollar deal in Moscow — a deal that would have been the most lucrative of his life — at the same time he is running for president just screams of compromise.”

During an appearance Wednesday at the National Press Club, Schiff said that although negotiating with the Russians while running for office may not be a matter for prosecutors, it could have made Trump vulnerable to foreign influence.

“It may not be a crime,” he said. “It is, however, a counterintelligence problem of the first order of magnitude.”

Troianovski reported from Moscow. Ellen Nakashima, Rachael Bade, Alice Crites, Karoun Demirjian, Rosalind S. Helderman and Devlin Barrett in Washington and Natalia Abbakumova in Moscow contributed to this report.