If Michael Hayden, the former head of the National Security Agency and the CIA, is worried about having his security clearance revoked, he is doing a good job of hiding it.

“In terms of the personal impact that the loss of a clearance would have on me, it’s almost zero,” the retired general told Federal Times in an interview Aug. 20.

But Hayden said that Trump’s threat to revoke security clearances from outspoken critics is worrisome “at the highest level” because of the precedent it sets.

"We should not pretend to ourselves that it is normal to deny something to a group of people that would be otherwise available to them except for their political speech,” Hayden said.

Earlier in August, the White House said it revoked the security clearance of former CIA chief John Brennan, who is a frequent critic of the president and the Trump campaign’s relationship with Russia. Hayden, who has also criticized Trump, is among nine current and former American officials who are having their security clearances reviewed.

The White House referred Federal Times to an Aug. 15 statement from Trump, which argued that access to America’s secrets should further national, and not personal, interests.

Hayden was among a group for former top intelligence officials who signed a letter saying they had never seen the approval or removal of security clearances be used as a political tool.

“This action is quite clearly a signal to other former and current officials,” the letter said.

When asked if the threats to revoke security clearances were causing concern inside the intelligence community, Hayden cited two more rounds of letters signed by 60 and 175 former officials.

“The country will be weakened if there is a political litmus test applied before seasoned experts are allowed to share their views,” one letter said.

“It’s hard to imagine if the alumni association is getting so excited about this, than those still in school wouldn’t be either,” Hayden said. “They just can’t say anything.”