- President Donald Trump’s former National Security Adviser John Bolton is being investigated for possibly disclosing classified information when he published his memoir in June.
The US Department of Justice launched a criminal case after failing to stop the publication of The Room Where It Happened book.
Mr Bolton denies all the accusations.
His work shows a president ignorant of geopolitical facts and whose decisions are driven by a desire for re-election.
At the time of publication, President Trump made it clear that he wanted his former aide prosecuted, describing him “grossly incompetent” and “a liar”.
Mr Bolton served as President Trump’s national security adviser in 2018-19.
The case would focus on Mr Bolton’s claim that his manuscript had passed through a pre-publication national security review, and claims by critics that it did not complete that review.
A grand jury convened by the Department of Justice has now formally issued subpoenas to the Simon & Schuster publishing company and the Javelin Agency, which represents Mr Bolton.
In a statement, Mr Bolton’s lawyer Charles J. Cooper said: “Ambassador Bolton emphatically rejects any claim that he acted improperly, let alone criminally, in connection with the publication of his book, and he will cooperate fully, as he has throughout, with any official inquiry into his conduct.”