John Brennan lobbed a “vicious” tweet at President Donald Trump on Sunday because the former CIA director fears his role in the spying on the chief executive’s 2016 campaign will be exposed, Judge Andrew Napolitano said Monday on Fox Business Network’s “Mornings with Maria.”

“One of the reasons, I think, that John Brennan’s tweet was so vicious in tone was because he does not want this behavior exposed,” Napolitano said. “He probably was behind it — and in fairness to him, it went on long before he got there and will go on long after he is gone.”

Napolitano was referring to Brennan’s tweet saying, “Senator [Mitch] McConnell & Speaker [of the House Paul] Ryan: If Mr. Trump continues along this disastrous path, you will bear major responsibility for the harm done to our democracy,” Brennan tweeted in response to Trump’s tweet. “You do a great disservice to our Nation & the Republican Party if you continue to enable Mr. Trump’s self-serving actions.”

Senator McConnell & Speaker Ryan: If Mr. Trump continues along this disastrous path, you will bear major responsibility for the harm done to our democracy. You do a great disservice to our Nation & the Republican Party if you continue to enable Mr. Trump’s self-serving actions. https://t.co/uAhgL6wfIC — John O. Brennan (@JohnBrennan) May 20, 2018

More from LifeZette TV

MORE NEWS: Bloomberg Pays Fines for 32,000 Florida Felons– So They can Vote!

Brennan was angered by Trump’s tweet earlier Sunday calling for the Department of Justice (DOJ) to open an official investigation to determine whether former President Barack Obama’s administration “infiltrated or surveilled” the Trump presidential campaign. The president was responding to multiple media reports that the bureau had an informant in the Trump campaign.

Do you agree that protesting is acceptable, but rioting is not? Yes No Email Address (required) By completing the poll, you agree to receive emails from LifeZette and that you've read and agree to our privacy policy and legal statement Results Vote

Deep in a story it published Thursday, for example, The New York Times reported that “at least one government informant met several times with Mr. [Carter] Page and [George] Papadopoulos,” two of Trump’s former campaign advisers.

“I hereby demand, and will do so officially tomorrow, that the Department of Justice look into whether or not the FBI/DOJ infiltrated or surveilled the Trump Campaign for Political Purposes — and if any such demands or requests were made by people within the Obama Administration!” Trump tweeted Sunday.

I hereby demand, and will do so officially tomorrow, that the Department of Justice look into whether or not the FBI/DOJ infiltrated or surveilled the Trump Campaign for Political Purposes – and if any such demands or requests were made by people within the Obama Administration! — Donald J. Trump (@realDonaldTrump) May 20, 2018

MORE NEWS: Texas Youth Summit urges conservative minded youth to be a shining light for truth

Sarah Isgur, the department’s spokeswoman, said DOJ Inspector General (IG) Michael Horowitz now will examine “whether there was any impropriety or political motivation in how the FBI conducted its counterintelligence investigation of persons suspected of involvement with the Russian agents who interfered in the 2016 presidential election,” according to The Wall Street Journal.

Deputy Attorney General Rod Rosenstein also said in a statement Sunday that “If anyone did infiltrate or surveil participants in a presidential campaign for inappropriate purposes, we need to know about it and take appropriate action.”

This wasn’t the first time that the decidedly anti-Trump Brennan unleashed a volley against the president via Twitter. In March 2018, Brennan ripped Trump for celebrating the firing of former FBI Deputy Director Andrew McCabe. Attorney General Jeff Sessions fired McCabe just before his retirement with a full pension was set to kick in after Horowitz reported that McCabe lied to FBI investigators.

“When the full extent of your venality, moral turpitude, and political corruption becomes known, you will take your rightful place as a disgraced demagogue in the dustbin of history,” Brennan tweeted at Trump. “You may scapegoat Andy McCabe, but you will not destroy America … America will triumph over you.”

When the full extent of your venality, moral turpitude, and political corruption becomes known, you will take your rightful place as a disgraced demagogue in the dustbin of history. You may scapegoat Andy McCabe, but you will not destroy America…America will triumph over you. https://t.co/uKppoDbduj — John O. Brennan (@JohnBrennan) March 17, 2018

Napolitano, a senior judicial analyst for Fox News, speculated that Brennan may have chosen to direct his most recent “vicious” tweet at Trump because “we may be on the precipice of exposing” a huge political scandal.

Although Napolitano admitted that “it shouldn’t surprise people that agents of the intelligence community inveigle their way into private entities because that happens all the time,” he emphasized that “we may be on the precipice of exposing a very, very extraordinary political use of intelligence and law enforcement by the Obama Administration.”

Fox Business host Maria Bartiromo slammed Obama for “politicizing all of his agencies” during his administration, including “the DOJ, the FBI, the IRS, the CIA.” She claimed “they were all involved in trying to take down Donald Trump.”

“Now, the other side of this is [that] the government can’t just investigate anyone it wants. There has to be articulable suspicion. That’s a rather low threshold, but it means the government must articulate why and for what law enforcement purpose it is gathering information about a person or an entity,” Napolitano explained.

As part of the review into the DOJ’s and FBI’s surveillance, the IG must discover and disclose “what information may have been obtained directly or surreptitiously and for what purpose from the Trump campaign,” Napolitano said.

Related: President Orders DOJ Probe of Its Spying on His 2016 Campaign

Multiple outlets reported that American former University of Cambridge scholar Stefan Halper was the suspected FBI informant.

“Did the professor inveigle his way into the Trump campaign because the FBI thought crimes were being committed, or because the White House wanted to know what the Trump campaign was doing so they could pass that information on to Hillary?” Napolitano wondered.

Trump’s decision to demand an investigation into the informant and the FBI’s conduct “is part of the [former New York City Mayor] Rudy Giuliani-inspired ‘Let’s go on the offense’ approach that the Donald Trump legal team has been taking lately,” Napolitano suggested.

Although Trump didn’t respond directly to Brennan on Twitter, he wrote three tweets quoting former Secret Service agent Dan Bongino on “Fox & Friends” Monday.

“‘John Brennan is panicking. He has disgraced himself, he has disgraced the Country, he has disgraced the entire Intelligence Community. He is the one man who is largely responsible for the destruction of American’s faith in the Intelligence Community and in some people at the … top of the FBI,” Trump began.

“‘Brennan started this entire debacle about President Trump. We now know that Brennan had detailed knowledge of the (phony) Dossier…he knows about the Dossier, he denies knowledge of the Dossier, he briefs the Gang of 8 on the Hill about the Dossier, which … they then used to start an investigation about Trump. It is that simple. This guy is the genesis of this whole Debacle. This was a Political hit job, this was not an Intelligence Investigation. Brennan has disgraced himself, he’s worried about staying out of Jail.’ Dan Bongino,” Trump concluded.

“John Brennan is panicking. He has disgraced himself, he has disgraced the Country, he has disgraced the entire Intelligence Community. He is the one man who is largely responsible for the destruction of American’s faith in the Intelligence Community and in some people at the…. — Donald J. Trump (@realDonaldTrump) May 21, 2018

….top of the FBI. Brennan started this entire debacle about President Trump. We now know that Brennan had detailed knowledge of the (phony) Dossier…he knows about the Dossier, he denies knowledge of the Dossier, he briefs the Gang of 8 on the Hill about the Dossier, which…. — Donald J. Trump (@realDonaldTrump) May 21, 2018

…they then used to start an investigation about Trump. It is that simple. This guy is the genesis of this whole Debacle. This was a Political hit job, this was not an Intelligence Investigation. Brennan has disgraced himself, he’s worried about staying out of Jail.” Dan Bongino — Donald J. Trump (@realDonaldTrump) May 21, 2018

PoliZette writer Kathryn Blackhurst can be reached at [email protected]. Follow her on Twitter.