Former CIA Director John Brennan says he has yet to hear from the White House after it threatened to strip him of his security clearance, as well as those of other former intelligence officials who served under former Presidents Barack Obama and George W. Bush.

"I have heard nothing other than what has come out from the White House spokesperson," Brennan said Tuesday on MSNBC.

The White House threatened on July 23 to revoke the security clearances of top former officials who have been critical of Trump. Among those officials were former FBI Director James Comey, former Deputy FBI Director Andrew McCabe, former CIA Director Michael Hayden, former national security adviser Susan Rice, and former Director of National Intelligence James Clapper. Comey, who was dismissed by Trump last year, and McCabe, who was fired in March, no longer have security clearances.

[Opinion: Trump has the authority to revoke security clearances. Should he?]

White House press secretary Sarah Sanders told reporters Trump was “exploring the mechanisms to remove security clearances because they politicized, and in some cases monetized, their public service and security clearances.”

Brennan said the White House has a “flawed understanding” of why former officials retain their security clearances. He explained that he has reviewed his personal CIA files “a number of times” since leaving the agency to prepare for congressional hearings, but has not requested any other briefings since stepping down.

The White House announcement came hours after Sen. Rand Paul, R-Ky., lobbied Trump to revoke Brennan’s clearance.

"I don't know anybody in the intelligence national security realms who takes what Rand Paul says seriously. But he continues to spout off on these issues," Brennan said.