When Attorney General William Barr stated "spying did occur" against the 2016 Trump campaign, most attention was focused on the FBI's surveillance of former junior foreign policy aide Carter Page.

But the spying Barr was thinking of, and which he said may or may not have been legally authorized, is more likely to be that carried out by Stefan Halper, a former Republican operative and White House aide who became a foreign policy academic with close ties to both American and British intelligence.

One could be forgiven for believing Halper was a creation of the spy novelist John Le Carré. A Cambridge don and White House veteran of the Nixon, Ford, and Reagan administrations, he has long operated in the gray area between academe and espionage. Gregarious, rumpled, and with an ample girth, Halper, now 74, was known as "Stef" to his friends and students, whom he would regale with tales of Washington intrigue.

While the FBI describes Halper as its "informant," he did far more than report things he became privy to in the course of his normal life. Rather, he actively courted at least three Trump campaign officials, offering to pay for travel and misrepresenting himself as eager to work for Trump.

During the 2016 presidential campaign, Halper was asked by the FBI to gather information on Page and George Papadopoulos, a foreign policy aide with a junior but more central role than Page, and he met with Trump campaign co-chairman Sam Clovis.

As Justice Department Inspector General Michael Horowitz’s investigation into alleged FISA abuse nears its conclusion in either May or June, new reports have emerged indicating that Halper has been looked at as part of that probe.

Halper graduated from Stanford in 1967 and received a Ph.D. from Oxford in 1971 and Cambridge in 2004. He was the director of American studies in the Department of Politics and International Studies at Cambridge, where he taught classes and also delivered papers at institutions around the world, including Chatham House in London, the Center for Strategic and International Studies in D.C., and the U.S. Naval War College. Halper is now the emeritus senior fellow of the Centre of International Studies.

At Cambridge, he worked for years alongside Sir Richard Dearlove, who had spent decades with MI6, the British Secret Intelligence Service, the equivalent of the CIA, and was its director from 1999 to 2004.

Christopher Steele, hired by Fusion GPS and the eventual author of the Trump dossier that was used in FISA applications to target Trump associates, was in MI6 from 1987 until 2009. Dearlove has described Steele as the “go-to person on Russia in the commercial sector” and said his reputation is “superb.”

Halper organized and hosted a series of Cambridge Intelligence Seminars that were attended by intelligence community members, academics, and researchers from around the world. One such seminar in 2014, put together by both Halper and Dearlove, was attended by then-President Barack Obama’s Defense Intelligence Agency Director Mike Flynn, who played a prominent role in the Trump campaign beginning in early 2016.

After Trump’s win, Flynn left his position as Trump’s national security adviser following questions about his contacts with Russian Ambassador Sergey Kislyak. He later pleaded guilty to lying to the FBI during special counsel Mueller’s investigation regarding his contacts with the ambassador.

Dearlove and Halper both stepped down from the Cambridge Intelligence Seminars amid reports that Russian operatives were attempting to compromise the organization. Halper said he left due to “unacceptable Russian influence on the group.”

Today, Dearlove is listed as the chairman and Halper is listed as a partner at the Cambridge Security Initiative, which states it “provides a unique link between the worlds of business, government, and academia with unrivaled expertise in security and intelligence issues.”

This is not the first time that Halper has been accused of spying on a presidential campaign. In the lead-up to the 1980 presidential election between then-President Jimmy Carter and candidate Ronald Reagan, briefing documents from the Carter campaign were allegedly leaked to Reagan’s team before the one and only presidential debate on Oct. 28, 1980. Dubbed “Debategate," the details on this scandal were not publicly revealed until 1983. And Halper was accused of being the person in charge of the operation, allegedly involving former CIA officials.

Though now on his second marriage, Halper’s father-in-law at the time was former top CIA official Ray Cline, best known for his key role in handling the Cuban Missile Crisis in 1962. Cline denied Halper’s involvement and downplayed the alleged operation, saying, “I think this is all a romantic fallacy about an old CIA network … Such an effort would not have been worthwhile and I believe it was not executed.” Halper has denied his involvement as well.

During the 2016 presidential campaign, Halper met with Page and Papadopoulos at the behest of the FBI as part of its investigation into possible collusion between the Trump campaign and Russia. Halper also met with Clovis, the Iowa-based national co-chairman of the Trump campaign, although it is not known if this was done with the authorization of the FBI.

Page, who was the subject of FISA warrants in 2016 and 2017, says he first met Stefan Halper in mid-July 2016, after receiving an invitation to one of Halper’s intelligence seminars, titled “2016’s Race to Change the World," in May or June 2016. Page said that organizers paid for his travel to and from the conference. Halper continued reaching out to Page into at least 2017.

Stefan Halper also contacted Clovis via email in late August 2016, and Halper referenced his conversations with Page as part of his offer to meet. Halper and Clovis met up in Virginia a few days later. Of their conversation, Clovis said, “It had nothing to do with emails. No mention of Russia. No mention of Hillary Clinton. No mention of her campaign. Only a mention in passing that he had met with Carter Page."

The FBI says it began its Trump-Russia investigation, dubbed “Crossfire Hurricane," in July 2016, just a couple weeks after Halper met with Page. A meeting involving Trump dossier author Steele, DOJ official Bruce Ohr, and his wife and Fusion GPS contractor Nellie Ohr occurred just before the launch of the investigation as well.

The Justice Department says its investigation was initiated following Australian diplomat Alexander Downer telling the FBI that Papadopoulos informed him at a London bar in the spring of 2016 that Russia had damaging information on Hillary Clinton.

Papadopoulos says that Halper sent him an unsolicited email in September 2016 asking to discuss foreign policy issues with him. “I’ll pay you $3,000 and I'll fly you to London, and let's talk about it for a couple days and let's see what you can do, and just write a paper for me,” Papadopoulos quoted Halper as saying. He met Halper in London and says that Halper grilled him about Hillary Clinton’s hacked emails, Russia’s involvement, and how it may have benefited the Trump campaign. Papadopoulos said, “I think I pushed back and I told him, 'I don't know what the hell you're talking about.'”

When Halper’s role as an FBI informant was leaked to the media in May 2018, it led to accusations from Trump and Republicans in Congress that the Obama Justice Department had been using Halper as part of an illegal effort to spy on the Trump campaign. Dubbed “Spygate” by allies of the president, the revelation led Trump to tweet that this was “starting to look like one of the biggest political scandals in U.S. history.”

Democrats argue that Halper’s role as an FBI informant amounted to “spying," though by any layman's view of the term, it did. Back in 2018, Trump addressed this, saying, “The Democrats are now alluding to [sic] the the concept that having an informant placed in an opposing party’s campaign is different than having a Spy, as illegal as that may be. But what about an ‘informant’ who is paid a fortune and who ‘sets up’ way earlier than the Russian Hoax?”

Halper was the author of several books on international relations that were critical of U.S. foreign policy from a traditional realist perspective. Co-written in 2004 with former British diplomat Jonathan Clarke, America Alone: The Neo-Conservatives and the Global Order was deeply critical of the Bush administration’s post-9/11 strategy of vast military action and “nation-building."

In 2007 he wrote The Silence of the Rational Center: Why American Foreign Policy is Failing on what he contended was the American obsession with “big idea” sloganeering rather than astute decision-making on the world stage. His 2012 book The Beijing Consensus spoke of China’s rapid rise, said that China “will not confront the West on the battlefield, but in the global information space," and warned that U.S. foreign policy was woefully unprepared to deal with this.

When Halper contacted members of the Trump campaign, he did so under the guise of discussing foreign policy.

The FBI’s investigation into Russia and the Trump campaign was rolled into special counsel Mueller’s investigation following his appointment in May 2017. Last month, Barr provided a four-page letter outlining the baseline conclusions of Mueller’s investigation, including the fact that Mueller did not charge any Trump associates with crimes related to collusion with Russia. Barr said Mueller did not reach a conclusion one way or the other on whether Trump committed obstruction of justice.

And Barr said that the Justice Department inspector general's investigation into possible FISA abuse by the DOJ and FBI should be done “probably in May or June.”

Congressional Republicans such as Rep. Devin Nunes, R-Calif., had fought for access to DOJ information on Halper’s relationship with the FBI. Nunes now says he has prepared a series of criminal referrals that he will be sending to the DOJ within days, and Attorney General Barr has said that he will take a serious look at the documentation that Nunes sends him. It is not known whether Halper will be part of any of the referrals.

After decades of being an accessible public figure well known to journalists, foreign policy aficionados, and intelligence officials on both sides of the Atlantic, Halper has retreated into the shadows, refusing all unknown callers to his rural home in Great Falls, Va.