WASHINGTON (Reuters) - Former CIA Director John Brennan said on Thursday he would not be silenced by Donald Trump, a day after the president revoked the Obama-era official’s security clearance and said the move was directly tied to the Russia investigation.

FILE PHOTO: Former CIA Director John Brennan arrives for a Senate Intelligence Committee hearing evaluating the intelligence community assessment on "Russian Activities and Intentions in Recent US Elections" on Capitol Hill in Washington, U.S., May 16, 2018. REUTERS/Leah Millis/File Photo

Retired Navy Admiral William McRaven, who oversaw the 2011 Navy SEAL operation that killed al Qaeda leader Osama bin Laden, responded to Trump’s move by praising Brennan and asking the president to revoke his security clearance as well.

In a statement on Wednesday, Trump said he revoked Brennan’s authorization for making what he called “unfounded and outrageous allegations” about his administration and was evaluating whether to strip clearances from other former top officials. Brennan and the others have criticized the Republican president.

Trump later told the Wall Street Journal his decision was connected to Special Counsel Robert Mueller’s probe into alleged Russian interference in the 2016 presidential election and alleged collusion by his campaign.

“I call it the rigged witch hunt, (it) is a sham,” Trump told the newspaper in an interview on Wednesday. “And these people led it.

“It’s something that had to be done,” Trump added.

The president has denied any collusion. Russia has said it did not interfere, contrary to U.S. intelligence agencies’ findings.

Brennan, who led the CIA under Democratic President Barack Obama, on Thursday called Trump’s denials “hogwash” and vowed not to be silenced.

“The only questions that remain are whether the collusion that took place constituted criminally liable conspiracy, whether obstruction of justice occurred to cover up any collusion or conspiracy, and how many members of ‘Trump Incorporated’ attempted to defraud the government by laundering and concealing the movement of money into their pockets,” Brennan wrote in an opinion article in the New York Times.

‘REVOKE MY SECURITY CLEARANCE’

Former U.S. Director of National Intelligence James Clapper, another critic whose clearance Trump said he might target, cautioned that Brennan was expressing “an informed opinion.” It remained up to Mueller to make a final conclusion, Clapper told CNN.

Mueller has indicted or secured guilty pleas from 32 people and three companies, including Russian intelligence officials and former Trump aides.

Senate Intelligence Committee Chairman Richard Burr said in a statement that if Brennan’s conclusion that the Trump campaign colluded with Russians was based on intelligence he has seen since leaving office, “it constitutes an intelligence breach.”

The Republican senator also said Trump has “full authority” to revoke Brennan’s security clearance.

High-ranking government officials sometimes retain security clearances after leaving office to advise their successors as needed, and some private-sector companies can also require them.

Former FBI Director James Comey and former National Security Agency director Michael Hayden, among others, could also see their clearances revoked. Bruce Ohr, a Justice Department official currently in the criminal division, was also on the White House list.

“I don’t trust many of those people on that list,” Trump told the Journal. “I think that they’re very duplicitous. I think they’re not good people.”

In a letter to Trump published in the Washington Post, retired Admiral McRaven, calling Brennan "one of the finest public servants I have ever known," said he "would consider it an honor if you would revoke my security clearance as well, so I can add my name to the list of men and women who have spoken up against your presidency." McRaven's name was not on Trump's list. (wapo.st/2PaA0AK)

“Through your actions, you have embarrassed us in the eyes of our children, humiliated us on the world stage and, worst of all, divided us as a nation,” wrote McRaven, who led the U.S. Joint Special Operations Command from 2011 to 2014.

Brennan does not face any formal charges of violating any regulations or laws. He has frequently criticized the president on television news shows and in blistering tweets that Trump on Wednesday called “wild outbursts.”

Reactions from Republican lawmakers were mixed, with some critical of Trump while others blamed Brennan for acting inappropriately.

Democratic lawmakers blasted the president’s move as dangerous. U.S. Representative Joaquin Castro said Mueller should also investigate the issue now that Trump has tied it to the Russia probe.

“It’s an abuse of power because he’s not doing it for a legitimate reason,” Castro told CNN.