The Washington Post took the unusual step of correcting and removing large portions of two articles, published in March 2017 and February 2019, that had identified a Belarusian American businessman as a key source of the "Steele dossier," a collection of largely unverified reports that claimed the Russian government had compromising information about then-candidate Donald Trump.

The newspaper's executive editor, Sally Buzbee, said The Post could no longer stand by the accuracy of those elements of the story. It had identified businessman Sergei Millian as "Source D," the unnamed figure who passed on the most salacious allegation in the dossier to its principal author, former British intelligence officer Christopher Steele.

The story's headline was amended, sections identifying Millian as the source were removed, and an accompanying video summarizing the article was eliminated. An editor's note explaining the changes was added. Other stories that made the same assertion were corrected as well.

Source D, according to the dossier, alleged that Russian intelligence had learned that Trump had hired Russian prostitutes to defile a Moscow hotel room once occupied by President Barack Obama and Michelle Obama and possessed a video recording of the incident.

The allegation, which the dossier said was confirmed by a second person described only as "Source E," has never been substantiated.

Steele's dossier consisted of raw information and unconfirmed tips from unidentified sources, which he compiled as part of a political opposition-research project for an investigative firm working on behalf of the Hillary Clinton 2016 presidential campaign. Though Steele shared it with the FBI, its contents remained largely unknown and unpublicized until two months after the 2016 election, when a leaked copy was published by BuzzFeed News.

Trump has repeatedly denounced the dossier as false, framing it as the centerpiece of a malicious effort financed by his political opponents to damage him.

The Post's reassessment follows the indictment on Nov. 4 of Igor Danchenko, a Russian American analyst and researcher who helped Steele compile the dossier. Danchenko was arrested as part of an investigation conducted by attorney John Durham, the special counsel appointed by Trump's attorney general William Barr to probe the origins and handling of the FBI's inquiry into Trump's alleged Russian connections.

Danchenko was indicted on charges that he repeatedly lied to the FBI about where and how he got information that he allegedly gave to Steele for the dossier. He pleaded not guilty in federal court this week. His attorney, Mark Schamel, said in a statement: "For the past five years, those with an agenda have sought to expose Mr. Danchenko's identity and tarnish his reputation while undermining U.S. National Security. This latest injustice will not stand."

Buzbee said the indictment and new reporting by the newspaper has "created doubts" about Millian's alleged involvement. The new reporting included an interview with one of the original sources in its 2017 article, who now is uncertain that Millian was Source D, she said. "We feel we are taking the most transparent approach possible" to set the record straight, she said.

The March 2017 Post story carried the headline, "Who is 'Source D'? The man said to be behind the Trump-Russia dossier's most salacious claim." It said Millian had been identified in different portions of the dossier as Source D and Source E. The article included Millian's repeated denials that he had helped Steele.

The newspaper removed references to Millian as Steele's source in online and archived versions of the original articles. The stories themselves won't be retracted. A dozen other Post stories that made the same assertion were also be corrected and amended.

The Post's decision to edit and repost the Millian stories is highly unusual in the news industry.

Mainstream publications often add corrections to published stories when credible new information emerges. Some publishers also enable readers to petition them to remove unflattering stories from their websites, a once-controversial practice that has gained more acceptance in the digital era, when articles can remain accessible online for years.

But it's rare for a publication to make wholesale changes after publication and to republish the edited story, especially more than four years afterward.

"No such case comes immediately or specifically to mind, at least no historical case that stirred lasting controversy," said W. Joseph Campbell, a professor and journalism historian at American University.

The February 2019 Post story detailed Millian's involvement in some of Trump's business activities. It was headlined, "Sergei Millian, identified as an unwitting source for the Steele dossier, sought proximity to Trump's world in 2016."

The indictment secured by Durham on Nov. 4 suggests, but doesn't explicitly assert, that Danchenko may have gotten his information about the hotel encounter not from Millian but from a Democratic Party operative with long-standing ties to Hillary Clinton. The indictment doesn't name the executive by name, but he has been identified as Charles Dolan Jr. by Dolan's attorney, Ralph Martin, who otherwise declined to comment because Dolan is a "witness in an ongoing case."

The indictment notes that the executive stayed at the Moscow Ritz-Carlton hotel where the alleged incident with prostitutes took place, and took a tour of the presidential suite in June 2016. The timing is consistent with Steele's later report about the alleged hotel-room encounter.

The Steele dossier was a basis for the FBI's legal arguments for surveillance of Carter Page, a former Trump campaign adviser, during the 2016 campaign. A Justice Department inspector general later criticized the agency for failing to note doubts about the veracity of the information in its application for court approval of the surveillance.

The 2017 and 2019 stories were written by veteran reporters Rosalind S. Helderman and Tom Hamburger. They declined to comment.

The Wall Street Journal first identified Millian as Steele's source in early 2017. A spokesman, Steve Severinghaus, said the paper is "aware of the serious questions raised by the allegations and continue[s] to report and to follow the investigation closely."

Buzbee became The Post's executive editor earlier this year. The two Millian stories were published under her predecessor, Martin Baron.