(CNN) President Donald Trump announced Wednesday he has revoked former CIA director John Brennan's security clearance, marking an unprecedented use of a president's authority over the classification system to strike back at one of his prominent critics.

"I have a unique constitutional responsibility to protect the nation's classified information, including by controlling access to it. Today, in fulfilling that responsibility, I have decided to revoke the security clearance of John Brennan, former director of the Central Intelligence Agency," Trump said in a statement dictated in the White House briefing room by his press secretary Sarah Sanders. "Mr. Brennan's lying and recent conduct characterized by increasingly frenzied commentary is wholly inconsistent with access to the nation's most closely held secrets."

Brennan is the first former national security official to see his security clearance revoked since the White House announced last month that Trump was considering taking that action against several of his most vocal critics in the national security world.

"This action is part of a broader effort by Mr. Trump to suppress freedom of speech & punish critics. It should gravely worry all Americans, including intelligence professionals, about the cost of speaking out. My principles are worth far more than clearances. I will not relent," Brennan tweeted after the announcement.

This action is part of a broader effort by Mr. Trump to suppress freedom of speech & punish critics. It should gravely worry all Americans, including intelligence professionals, about the cost of speaking out. My principles are worth far more than clearances. I will not relent. https://t.co/TNzOxhP9ux — John O. Brennan (@JohnBrennan) August 15, 2018

The decision comes as the White House is looking to turn the page on a news cycle that for several days has been dominated by startling allegations leveled against Trump by Omarosa Manigault-Newman, a former senior White House official and longtime Trump adviser.

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