The National Security Council "has determined that the manuscript in its present form contains certain passages - some up to several paragraphs in length - that contain classified national security information", the Justice Department alleged at the time.
"We are aware of reports that grand jury subpoenas have been issued seeking information concerning the publication of Ambassador Bolton's recent book", Bolton's lawyer Chuck Cooper said in a statement.
The subpoenas were issued to Simon & Schuster and to Javelin, according to multiple reports on Tuesday citing unnamed officials. Trump has torn into the book (and Bolton himself) ever since its publication was announced, denouncing his former official as a "sick puppy" and dismissing the "scandals" detailed in the memoir as "a compilation of lies and made-up stories, all meant to make me look bad".
After viewing classified declarations and discussing them in a closed hearing, Judge Lambert also said that he was "persuaded that defendant Bolton likely jeopardized national security by disclosing classified information in violation of his nondisclosure agreement obligations". Soon after, however, Bolton was informed that the review was still ongoing and that a separate NSC official determined it still contained passages with classified information.
The unlikely liberal champion has kept up his attacks on the president since the book's release, appearing on CNN on Monday to deride Trump as a "useful idiot" in his geopolitical dealings with Russia, China, and North Korea.
An attorney for Bolton did not immediately return a request for comment.
"Bolton has gambled with the national security of the United States", Judge Lamberth wrote. "But these facts do not control the motion before the court".
Bolton, who served for a time as President Donald Trump's national security adviser, has said he has complied with all of the revisions requested by the White House.
Trump, meanwhile, sought to frame the judge's ruling as a "big court win against Bolton". "Bolton broke the law and has been called out and rebuked for so doing, with a really big price to pay".
"This was Bolton's bet: If he is right and the book does not contain classified information, he keeps the upside. but if he is wrong, he stands to lose his profits from the book deal, exposes himself to criminal liability, and imperils national security".
National security attorney Bradley Moss described the criminal probe as "absolutely an overtly political act", but said it was unclear whether that would be enough to beat back potential criminal charges for Bolton.