Washington (CNN) Omarosa Manigault Newman's secret recordings from her time in the White House are an "unthinkable" security violation, said former Director of National Intelligence James Clapper on Monday.

"It's a very serious and egregious security violation," Clapper said on CNN's "Erin Burnett OutFront" of bringing a phone into the White House Situation Room.

"It's sort of an honor system where everybody knows not to do that."

The former contestant on "The Apprentice" and ex- aide to President Donald Trump made waves Sunday by airing a secret recording of her firing from the White House by chief of staff John Kelly on NBC's "Meet the Press." The next day, she released another recording, this time of Trump, during an appearance on NBC's "Today" show.

Clapper added, "You're expected as a responsible member of the President's security team not to do that. ... So it's just kind of unthinkable that that would happen."

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