Trump's White House staffer NDA included a clause that required his permission before publishing tell-all books

The non-disclosure agreement top aides in the Trump White House signed included a clause that barred them from publishing tell-all books without the president's explicit approval.

Politico reported that the two-page NDA included a clause that prohibits aides from discussing "any confidential information" in any form — including in published books — without Donald Trump's explicit approval. If they violated the clause, aides would have to turn over all royalties, advances or earnings to the government.

"It’s not unusual for former administration officials to negotiate with the White House over the anecdotes and insider details of their books," the report noted. "But the terms of the White House’s NDA — and even the decision to compel government officials sign an NDA at all — are unprecedented."

Experts argue that a gag order like the one Trump reportedly made staffers sign would likely be unconstitutional.

The existence of the NDA was hinted at by Trump himself on Twitter Monday after his former aide and Apprentice contestant Omarosa Manigault Newman played recordings from her time in the White House on-air over the weekend.

"Wacky Omarosa already has a fully signed Non-Disclosure Agreement" the president tweeted mid-day on Monday.

Manigault Newman isn't the only former Trump aide to go public about her time in the White House. Former press secretary Sean Spicer has been on a book tour for weeks after the release of his book, "The Briefing: Politics, the Press, and the President," and his fellow former press secretary Anthony Scaramucci is slated to release his book this fall. Publisher's Weekly noted that former national security adviser H.R. McMaster is also publishing a book titled "Battlegrounds," which is set to be released in 2020.

This story is developing ...