Retired British spy Christopher Steele is stepping out of the shadows to discuss his so-called “Steele dossier” for the first time publicly, describing his efforts as apolitical and defending his decision to include the most explosive and criticized claims about Donald Trump contained in his controversial 2016 report.

“I stand by the work we did, the sources that we had, and the professionalism which we applied to it,” Steele said in a wide-ranging exclusive interview with ABC News’ George Stephanopoulos about how he gathered his intelligence, and the life-altering events that ensued after his work and identity were made public.

The dossier’s contents, laid out in 17 memos, upended Washington and quickly ricocheted across the globe after BuzzFeed News published the bombshell reports in early 2017 — 10 days before Donald Trump was sworn into office. The salacious mix of sex, spies, and scandal made for an irresistible political drama. But the real-world implications of its claims, even though unproven, exacerbated an already fraught moment in American history.

Trump and his allies immediately lashed out at the allegations laid out in the dossier, calling it “fake news” and “phony stuff.” The president’s detractors embraced it, using it to buttress growing suspicions about what they saw as Trump’s odd infatuation with Russian President Vladimir Putin.

MORE: Video ‘Out of the Shadows: The Man Behind the Steele Dossier’ | Oct 18 only on Hulu

Over time, journalists and experts from both sides of the political aisle grew increasingly skeptical about the dossier’s claims, noting that despite deep investigation by Special Counsel Robert Mueller’s team and others, many of Steele’s allegations have never been verified, and some have been debunked.

“Everyone with whom the dossier was shared sent reporters out, tried to confirm the basic allegations within it. And it never got any traction because no one could nail anything in it down,” said Barry Meier, author of “Spooked: The Trump Dossier, Black Cube, and the Rise of Private Spies,” and a vocal critic of Steele’s.

“Bearing in mind, this was raw intelligence,” said Chris Burrows, Steele’s partner in the private investigative firm Orbis Business Intelligence. “Raw intelligence in the sense that what we sent over was the initial findings.”

Yet in many ways, the dossier proved prescient. The Mueller probe found that Russia had been making efforts to meddle in the 2016 campaign, and that Trump campaign members and surrogates had promoted and retweeted Russian-produced political content alleging voter fraud and criminal activity on the part of Hillary Clinton. Investigators determined there had been “numerous links — i.e. contacts — between Trump campaign officials and individuals having ties to the Russian government.” And, proof emerged that the Trump Organization had been discussing a real estate deal in Moscow during the campaign.

All were findings that had been signaled, at least broadly, in Steele’s work.

Cloistered in his London home and his firm’s office, Steele has never responded to his critics in public. Through all the cacophony of political rhetoric and cable news punditry, one notable voice has been missing: Steele’s.

Now, nearly five years after his report became public, Steele has broken his silence to defend his name, his credibility, and the dossier that captured the world’s attention.

“It was credible reporting,” Steele told Stephanopoulos. “We knew some of it was right, and we suspected some of it may never be provable.”

“Out of the Shadows: The Man Behind the Steele Dossier” is available Monday, October 18, on Hulu.

A sordid conspiracy

Christopher Steele penned his reports between June and December of 2016 for a law firm that represented Democrats and the campaign of party nominee Hillary Clinton. His reporting was initially meant to be internal work for the firm conducting opposition campaign research.

Over seven months, the memos laid out a series of damning claims alleging that the Russians were attempting to influence the campaign in Trump’s favor, that members of the Trump campaign had various connections and communications with Kremlin officials, that the campaign had coordinated with Kremlin officials and accepted a flow of anti-Clinton information, and, most alarmingly, that the Kremlin perhaps had materials with which it could blackmail or exercise leverage over Trump.

Steele said that as he worked on the report, he grew increasingly alarmed by the picture it was painting.

“It meant that, for the first time, there was a potentially serious situation of ‘kompromat’ against a presidential candidate. And therefore, it became much more of serious issue than we had expected,” Steele recalled. “I was surprised and shocked.”

Even before the dossier surfaced publicly on Jan. 10, 2017, the FBI and several news outlets had already seen Steele’s intelligence reports and had attempted to corroborate their contents, but could not. Within days of its publication, some allegations fell apart quickly. Reports that Trump’s personal attorney and self-described fixer Michael Cohen had relatives who maintained ties to Putin were swiftly debunked.

Trump’s allies mounted a full-fledged campaign to pick the dossier apart — and malign its author. Trump himself repeatedly lashed out at Steele and the report. At one point, then-President Trump tweeted of Steele: “This man should be extradited, tried, and thrown into jail. A sick lier [sic] who was paid by Crooked Hillary & the DNC!”

Asked if he was ever worried about Trump’s calls for his extradition, Steele at first laughed: “He also called me a liar, spelled L-I-E-R, George. So, you know, these things have to be taken, I think, with a pinch of salt.”

But Steele said that the ensuing investigations, legal fights, and withering attacks — including Trump’s claims that his reporting was a “hoax” — did take a toll.

“The idea that somebody with my track record — and I’ve never had my integrity, professionalism, or expertise on Russia questioned at any point in my career — would be inventing some strange, fabricated document or information, is absolute anathema, and I wouldn’t be a successful businessman if that were the practice,” Steele said.

The dossier did deal a series of blows to Steele’s credibility in both media and government investigations, most notably a December 2019 Justice Department inspector general report that cast doubts on his sources.

The inspector general wrote that “certain allegations” in Steele’s reporting “were inaccurate or inconsistent with information gathered by the Crossfire Hurricane team; and that the limited information that was corroborated related to time, location, and title information, much of which was publicly available.”

“Do you accept that conclusion?” Stephanopoulos asked Steele.

“I think they are putting too much store, frankly, into what FBI knew about early on in the campaign,” Steele said. “I think the FBI is generally an effective organization. I’m not sure the extent to which FBI has got good coverage of Moscow and Moscow politics and Moscow operations.”

Through it all, Steele said, he has remained confident in the broad strokes of his dossier, which he insists remain “still very credible.”

“I think there are parts of the dossier which have been stood up, there are parts of the dossier that haven’t been stood up,” Steele said. “And there are one or two things in it which have been proven wrong.”

Drafting the dossier

Steele’s firm agreed to take on the project at the behest of Fusion GPS, a Washington-based corporate research firm, in the spring of 2016. Fusion GPS’s initial client had been a Republican financier, but when Trump emerged as the front-runner for the Republican nomination, a law firm representing the Democratic National Committee and the Clinton campaign agreed to inherit Fusion GPS’s research.

Steele said he knew within the first month of his reporting that “supporters of Hillary Clinton” were funding Fusion GPS’s work, and by extension his own.

“I didn’t know what opposition research was,” Steele said. “But from our perspective, what we were doing was very similar to other project work we’d done, which is getting human intelligence out of Russia on an issue of interest to a client.”

Fusion GPS co-founder Glenn Simpson told the Senate Judiciary Committee the assignment for Steele was relatively simple — Donald Trump had made repeated trips to Russia during his career as a real estate mogul, but not sealed any deals.

“He was the lead Russianist at MI6 prior to leaving the government and an extremely well-regarded investigator, researcher, and, as I say, we’re friends and share interest in Russian kleptocracy and organized crime issues,” Simpson testified regarding Steele. “I would say that’s broadly why I asked him to see what he could find out about Donald Trump’s business activities in Russia.”

Steele told ABC News that the mission expanded almost immediately into two main threads: “One was what the Russians were doing in terms of potential interference in the campaign; and two, what the links were between Trump and the Trump campaign and Russia,” Steele said.

“We realized it was potentially quite a big project and potentially quite a controversial project,” he added. “But frankly, George, when we went into it, we weren’t expecting to find a great deal.”

Steele soon became convinced he had wandered into something more involved, and more concerning.

The four pillars

In defending his work, Steele describes his intelligence reports as resting on “four pillars” of information that he believes have held up over time as accurate.

“One was, there was a large-scale Russian interference campaign in the American election in 2016,” he said.

“The second was that this had been authorized and ordered at the highest levels, including Putin,” he said.

“The third had been that the objective of this was to damage Hillary Clinton and to try and get this rather unorthodox candidate, Donald Trump, elected,” Steele said. “And the fourth was, there was evidence of collusion between Trump and people around Trump and the Russians.”

Part of the challenge — and the intrigue — of Steele’s reporting is that much of it is virtually impossible for lay people to verify. When the Department of Justice’s inspector general examined the dossier’s claims, he concluded that what Steele described as “raw intelligence” amounted to little more than rumor and bar talk.

Very little corroborating evidence has emerged to support the dossier. But neither, Steele points out, has there been much concrete contradictory evidence either.

His critics have taken issue with that particular line of defense.

“The common refrain when people were speaking about the dossier is, ‘Well, we don’t know if that’s not true,'” Meier said. “People who are intelligence operatives anchor their reports to rumors, to hearsay, to bar talk, to smoke. That’s the world that Christopher Steele operated in. And I guess that’s the world he continues to operate in. I prefer the world of facts. That’s the world I’m comfortable in.”

It isn’t just Steele’s critics who have accused him of trafficking in rumors. His own collector — the person who actually traveled to Russia on his behalf to gather information, including the “pee tape” allegation — later told the FBI that he “felt that the tenor of Steele’s reports was far more ‘conclusive’ than was justified,” and that “information came from ‘word of mouth and hearsay’ … ‘conversation that [he/she] had with friends over beers,'” according to a Justice Department inspector general report.

Steele suggested his collector may have “taken fright” at having his cover blown and “[tried] to downplay and underestimate” his own reporting when he spoke to the FBI. Steele added that the information he gathered passed through an important filter: his experience as an expert on Russian intelligence activities going back decades. He said his confidence in the dossier’s claims about Russia’s interest in Trump is based on his knowledge of Putin — a figure whom he has studied for decades.

“This is the M.O. of the KGB and its successor organizations,” Steele said, referring to Russia’s intelligence services.

Skeptics of Steele’s reporting, however, suggest he may have fallen victim to another trademark of Russian spy craft: disinformation. Speaking to congressional investigators in October 2019, Fiona Hill, a former National Security Council official in the Trump administration and a longtime friend of Steele’s, called Steele’s dossier a “rabbit hole.”

“It’s very likely that the Russians planted disinformation in and among other information that may have been truthful, because that’s exactly, again, the way that they operate,” Hill said.

Steele acknowledged that “there is a chance” the Russians intentionally tainted his reporting, but said he felt it was “very unlikely.”

“Ultimately, any disinformation operation has an objective,” Steele said. “Seems to me pretty far-fetched that the Russians’ objective during the campaign of 2016 was to aide Hillary Clinton and to damage Donald Trump. And I just don’t think you can get past that.”

The ‘pee tape’

One allegation from Steele’s dossier stood out immediately: a claim that the Russians had obtained a compromising video of Trump at the Ritz-Carlton Hotel in Moscow in 2013. According to the dossier, the tape purportedly showed Trump “employing a number of prostitutes to perform a ‘golden showers’ (urination) show in front of him” on a bed where the Obamas supposedly once stayed.

The supposed “pee tape” never emerged. But the claim may be the public’s most enduring symbol of Steele’s work — particularly after it became a favorite of late-night comics.

Steele told ABC News he believes the alleged tape “probably does” exist — but that he “wouldn’t put 100% certainty on it.”

When Stephanopoulos asked him to explain why the tape, if it does exist, has not been made public, Steele replied that “it hasn’t needed to be released.”

“Because I think the Russians felt they’d got pretty good value out of Donald Trump when he was president of the U.S.,” Steele said.

“[Putin] wouldn’t be releasing it in a hurry for all sorts of reasons,” he continued. “He would put it under very strict lock and key and make sure it never got out, unless he chose for it to get out.”

For his part, Trump has repeatedly and firmly denied this specific allegation. At a press conference the day after BuzzFeed published Steele’s dossier, Trump told reporters that he was “a germaphobe.” As recently as last week, Trump reportedly told donors at a private speech that he is “not into golden showers.”

Pressed by Stephanopoulos on how he can assess the likelihood of a seemingly outlandish allegation without concrete evidence, Steele cited his lengthy career as a British intelligence officer focused on Russia.

“When you’ve worked on Russia for 30 years like I have and you’ve spent as much time, sadly, in the brains of the Russian leadership as I have, you begin to understand these things,” Steele said. “And you actually sense whether something’s credible or not.”

Still defiant

Steele’s dossier took its first major hit with the release of special counsel Robert Mueller’s highly anticipated report, which largely omitted mention of Steele’s name or his claims. The most significant mention of Steele was not positive.

The report cast doubt on one of the dossier’s most striking claims: that Michael Cohen, Trump’s former personal attorney, had traveled to Prague in the summer of 2016 for “secret meeting/s with Kremlin officials.”

Cohen has vehemently denied ever traveling to Prague or meeting with Russian interlocutors. The Justice Department inspector general reinforced Mueller’s findings, saying the FBI had determined that this specific allegation was untrue.

To this day, Steele says he remains unmoved.

“Do you accept that finding, that it didn’t happen?” asked Stephanopoulos.

“No,” Steele replied. “I don’t.”

“But the FBI looked into this and said it wasn’t true,” Stephanopoulos said.

“I don’t know to what extent they were able to look into it. I don’t know what evidence they gathered,” Steele said. “I haven’t seen any, if you like, report on that aspect. So, from my point of view, I think it’s still an open question.”

Reached for comment, Cohen sarcastically told ABC News, “I’m pleased to see that my old friend Christopher Steele, a/k/a Austin Powers, has crawled out of the pub long enough to make up a few more stories.”

“I eagerly await his next secret dossier which proves the existence of Bigfoot, the Loch Ness Monster and that Elvis is still alive,” Cohen said.

Stephanopoulos pressed Steele: “Do you think it hurts your credibility at all that you won’t accept the findings of the FBI in this particular case?”

“I’m prepared to accept that not everything in the dossier is 100% accurate,” Steele replied. “I have yet to be convinced that that is one of them.”

Dismissing claims that subsequent government reports undermined his findings, Steele argued that, in his view, Mueller’s team actually served to reinforce the broad strokes of his dossier — those “four pillars” he described.

“Those four pillars that we mentioned … when you actually look at the detail, if you’re forensic about looking at the detail of the report, then it paints a totally different picture, in my view,” Steele said. “And I think there’s a lot of supportive commentary and evidence and so on, there, for the work we had done.”

But further investigative efforts undertaken at various levels of government have appeared to confirm the notion that Steele’s reporting was at best flawed and at worst incorrect.

A bipartisan report published by the Senate Intelligence Committee in April 2020 found that Steele’s assertions about Trump campaign aide Carter Page — which accused him of conducting “secret meetings in Moscow” with Kremlin leaders — were incorrect. Page himself would later testify before Congress that he spoke briefly with a mid-level Russian official during a visit for a Moscow speech, but that the conversation was short and inconsequential.

“Other than … facts which were readily available in news reports at the time of their inclusion in the dossier — the Committee did not find any information that corroborates the allegations related to Page in the dossier,” the report concluded.

Stephanopoulos asked Steele about the FBI decision to rely in part on his work in seeking and obtaining court approval to eavesdrop on Page under the Foreign Intelligence Surveillance Act (FISA).

“Any regrets about that?” Stephanopoulos asked.

“It had nothing to do with us,” Steele replied. “I didn’t even know what FISA was, frankly, in 2016. We were not told of any use of our material in such a process. And therefore, if there were problems with that process, they weren’t our problems, they were the problems of the people conducting it.”

A potential threat

Steele conceded in the ABC News interview that he could not provide evidence for many of his claims, including those about Page. But pressed by Stephanopoulos on some of the findings that have come up against the harshest criticism, Steele remained defiant.

“Not the ‘pee tape,’ not Michael Cohen in Prague, not Carter Page?” asked Stephanopoulos.

“None of those things, to my mind, have been disproven,” Steele replied. “They may not have been proven. And we maybe will hear more about those things as we go forward.”

Steele said he is watching American politics from a distance these days. He said he has concerns about a potential Trump return to the presidency in 2024.

“So, Donald Trump, in your view, is a continuing threat, as long as he’s an active political player, to the national security?” Stephanopoulos asked.

“A potential one,” Steele replied. “Yes.”

And as long as Trump remains active in politics, Steele contends that more evidence to support the dossier’s claims may still surface.

“I don’t think this book is finished,” Steele said. “By a long shot.”

ABC News’ Julia Macfarlane contributed to this report.