White House national security adviser Robert O'Brien said on Sunday that a transcript of a forthcoming memoir by his predecessor, John Bolton John BoltonThe Hill's Morning Report - Sponsored by The Air Line Pilots Association - Pence lauds Harris as 'experienced debater'; Trump, Biden diverge over debate prep DOJ launches probe into Bolton book for possible classified information disclosures Gary Cohn: 'I haven't made up my mind' on vote for president in November MORE, was not leaked by National Security Council (NSC) officials.

O'Brien said on CBS's "Face the Nation" that he's talked to members of the NSC and they did not leak the transcript, which was first reported last week by The New York Times.

"I'm very confident that that the leaks of that book did not come from the NSC," O'Brien said.

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According to the reported transcript, Bolton claims President Trump Donald John TrumpBarr criticizes DOJ in speech declaring all agency power 'is invested in the attorney general' Military leaders asked about using heat ray on protesters outside White House: report Powell warns failure to reach COVID-19 deal could 'scar and damage' economy MORE tied Ukrainian aid to investigations into former Vice President Joe Biden Joe BidenThe Memo: Warning signs flash for Trump on debates Senate Republicans signal openness to working with Biden National postal mail handlers union endorses Biden MORE. The claims corroborate allegations made by Democrats in impeachment charges against Trump.

Did recently leaked excerpts from John Bolton’s yet-to-be-published memoir come from the NSC? “I’m very confident that the leaks of that book did not come from the NSC,” National Security Advisor Robert O’Brien tells @margbrennan pic.twitter.com/aBGElmwMNT — Face The Nation (@FaceTheNation) February 2, 2020

The NSC said a review of Bolton's manuscript determined it contained classified information.

Bolton's lawyer, however, said that he and the former White House official disagree, pushing back on the White House's attempt to block the book from being published.

O'Brien said on Sunday that the NSC will "continue to be in touch" with Bolton.

"They'll continue to be in touch with Ambassador Bolton's lawyer, because what we need to do as the National Security Council is to make sure that state secrets and important classified information that could jeopardize American lives are not released," he added.