The Justice Department is demanding identifying details about the senior Trump administration official who has written an anonymous book, warning in a letter to the publisher on Monday that the author may be subject to nondisclosure agreements.

The letter, signed by Assistant Attorney General Joseph Hunt, asked for details or copies of the author's nondisclosure agreements "or the dates of the author's service and the agencies where the author was employed, so that we may determine the terms of the author's nondisclosure agreements and ensure that they have been followed."

Publication of the book may violate nondisclosure agreements based on the individual's work or access to classified information, the letter states, "if the author is, in fact, a current or former 'senior official' in the Trump administration."

Hachette Book Group confirmed that they'd received a letter from the Trump administration and said that they would not comply with the requests because the publisher is not party to any contracts with the U.S. government and intends to keep the author's identity secret.

"Hachette has, however, made a commitment of confidentiality to Anonymous and we intend to honor that commitment," the publisher said. "Please be assured that Hachette takes its legal responsibilities seriously and, accordingly, Hachette respectfully declines to provide you with the information your letter seeks."

The letter was first reported by CNN.

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The author's literary agency, Javelin, accused the administration of trying to "intimidate and expose" the official in a statement.

"Our author knows that the President is determined to unmask whistleblowers who may be in his midst. That's one of the reasons 'A WARNING' was written," the literary agency, Javelin, said in a statement, referring to the soon-to-be-published book. "But we support the publisher in its resolve that the administration's effort to intimidate and expose the senior official who has seen misconduct at the highest levels will not prevent this book from moving forward."

The senior Trump administration official first debuted as an anonymous critic in a 2018 New York Times op-ed, claiming that they and others sought to thwart the president's agenda from inside the government.

Last month, the publisher announced the forthcoming book, which will be published Nov. 19, as an "unprecedented behind-the-scenes portrait of the Trump presidency" and "a shocking first-hand account of President Trump and his record."

The president responded to the anonymous official's first op-ed by tweeting "TREASON?" and claiming there were national security concerns.