On the first anniversary of the appointment of special counsel Robert S. Mueller III to take over the investigation of Russian interference in the 2016 presidential campaign and any overlap with Donald Trump’s campaign, now-President Trump used his preferred political superlatives to disparage that inquiry on Twitter.

First it was a “witch hunt.” Then, after watching a segment on “Fox and Friends” featuring the National Review’s Andrew McCarthy, the investigation was “bigger than Watergate.”

That latter claim hinged on a column by McCarthy from last week speculating about the presence of an FBI informant embedded in Trump’s campaign. McCarthy points to testimony from Glenn Simpson of Fusion GPS, the firm hired by lawyers working for the Democratic National Committee and the Hillary Clinton campaign to investigate Trump in 2016. When that testimony was made public, we assessed Simpson’s comments and noted that individuals close to Fusion GPS told reporters that the comment was a reference to George Papadopoulos.

Papadopoulos is the campaign adviser who was told about the Russians having dirt on Clinton in April 2016 and then revealed that information to an Australian diplomat over drinks at a London bar that May. Once WikiLeaks began dropping files stolen from the DNC in July 2016, that diplomat told the FBI what he knew, a revelation that has been cited as the reason the FBI began its counterintelligence investigation of the Trump campaign in late 2016.

McCarthy is skeptical of that being the prompt for the investigation and skeptical that Simpson was referring to Papadopoulos. He argues instead that the trigger was some other individual in Britain. On “Fox and Friends,” he said there was “probably no doubt that they had at least one confidential informant in the campaign” and notes that FBI agents traveled to England as part of the investigation.

A long article published Wednesday by the New York Times bolsters the idea that there was an informant.

“At least one government informant met several times with Mr. [Carter] Page and Mr. Papadopoulos, current and former officials said,” the Times reports. “That has become a politically contentious point, with Mr. Trump’s allies questioning whether the F.B.I. was spying on the Trump campaign or trying to entrap campaign officials.”

White House counselor Kellyanne Conway put it succinctly in another Fox News Channel interview: “It looks like the Trump campaign may have been surveilled.”

Conway and Trump clearly have a vested interest in presenting the FBI and Mueller investigations (the latter having subsumed the former last May) as targeting Trump broadly. It’s not clear from news reports, though, whether that’s accurate. To get a sense of whether such rhetoric is justified, The Washington Post spoke by phone with James Pledger, who retired from the FBI as a section chief in 1996 after 30 years of service.

Pledger’s assessment of the investigation in broad terms was a skeptical one. He noted how he’d seen FBI culture shift since he left the bureau and appeared to be concerned about the genesis of this investigation in particular. But his view of the question posed by Trump was a cautious one.

The FBI’s investigation appears to have focused at the outset on four people associated with the Trump campaign: Papadopoulos; Page, a campaign adviser; retired Lt. Gen. Michael T. Flynn; and campaign chairman Paul Manafort. Pledger noted that there was clearly a difference between looking at bad actors and an investigation of an organization.

“If you talk about any large organization — if it’s a business, a company, a campaign — obviously it’s a large number of people, and people often are exploring opportunities for either sales or new contracts or ways to get advantage over their competition. That’s normal business,” he said. “If you do get somebody that steps over the line and does something that’s potentially criminal, that’s obviously something that needs to be looked at.”

Investigating people isn’t the same as investigating the Trump campaign, any more than investigating an executive at a Fortune 500 company in connection with embezzlement is an investigation of that company. That distinction — which may not be a fair one in this case — matters.

How an informant tried to suss out information about that potential bad actor also matters. An informant sidling up to a person of interest at a bar and striking up a conversation is very different from being someone hired at that Fortune 500 company to sit alongside them as they went about their workday. That difference speaks to where the focus of the investigation lies — and was important to Pledger.

“Putting a cooperating witness or an informant inside the campaign?” he said. “That would be on the outside of what I would think would be acceptable investigative techniques.”

It’s not clear how an informant seeking information about people associated with the Trump campaign might have gone about doing so. It’s also not clear how the FBI evaluated the credibility of the information it received. Pledger was skeptical, for example, that the FBI would assign a lot of credibility to one set of comments made by Papadopoulos over drinks. That said, he also noted that a counterintelligence investigation had a lower bar than a criminal case.

“Counterintelligence investigations” — like the one started in July 2016 — “are different than criminal. In criminal investigations, you have to establish a threshold of reasonable belief that a crime has occurred,” he said. “Intelligence is totally different. They can open a case and they can fish around a bit.”

Nonetheless, Pledger thought that there was some justification for Trump’s team feeling that it was under surveillance.

“The source is reaching out to multiple people who are involved in the campaign in different aspects,” he said, “so I think they’re probably looking for a conspiracy. Is it one person, one rogue employee trying to do something, or is it an orchestrated campaign on the part of the campaign to enlist another country to do something improper in our election process?” He noted that the FBI already had indications that the Russians were hoping to interfere in the campaign, meaning that it probably would have been more interested in learning more than simply whether Russia had contacts with people working for Trump.

Interestingly, Pledger’s career at the bureau meant that he was actually involved in the Watergate investigations.

“There are some parallels” to Watergate he said. But, he added, “I don’t think any of us know enough of the predicate information that was there — in the public, anyway — to make a firm assessment of whether it was proper or not,” referring to the FBI investigation.

Politics, of course, often outruns the information at hand.