John Bolton pleaded not guilty Friday to charges accusing the former President Donald Trump national security adviser turned critic of emailing classified information to family members and keeping top secret documents at his Maryland home.

Bolton was ordered released from custody after making his appearance before a judge in the third Justice Department case brought in recent weeks against an adversary of the Republican president.

The case accusing Bolton of putting the country's national security at risk is unfolding against the backdrop of growing concerns that the Trump administration is using the law enforcement powers of the Justice Department to pursue his political foes.

Bolton has signalled he will argue he is being targeted because of his criticism of the president, describing the charges as part of a Trump "effort to intimidate his opponents.”

The investigation into Bolton, however, was already well underway by the time Trump took office a second time this past January and appears to have followed a more conventional path toward indictment than other recent cases against perceived Trump foes, who were charged by the president's hand-picked US attorney in Virginia over the concerns of career prosecutors.

Bolton is accused of sharing with his wife and daughter more than 1,000 pages of notes that included sensitive information he had gleaned from meetings with other US government officials and foreign leaders or from intelligence briefings.

Authorities say some of the information was exposed when operatives believed to be linked to the Iranian government hacked Bolton's email account he used to send the diary-like notes about his activities to his relatives.

The Justice Department also alleges Bolton stored at his home highly classified intelligence about a foreign adversary's plans to attack US forces overseas, covert action taken by the US government and other state secrets.

“There is one tier of justice for all Americans,” Attorney General Pam Bondi said in a statement Thursday. “Anyone who abuses a position of power and jeopardizes our national security will be held accountable. No one is above the law.”

Bolton, 76, is a longtime fixture in Republican foreign policy circles who became known for his hawkish views on American power and who served for more than a year in Trump's first administration before being fired in 2019. He later published a book highly critical of Trump.

The indictment is significantly more detailed in its allegations than earlier cases against former FBI Director James Comey and New York Attorney General Letitia James. Unlike in those cases filed by a hastily appointed US attorney, Bolton's indictment was signed by career national security prosecutors.

Case centres on top secret national security information

Bolton suggested the criminal case was an outgrowth of an unsuccessful Justice Department effort after he left government to block the publication of his 2020 book “The Room Where It Happened,” which portrayed Trump as grossly misinformed about foreign policy.

Bolton's lawyers have said he moved forward with the book after a White House National Security Council official, with whom Bolton had worked for months, said the manuscript no longer had classified information.

Authorities say Bolton took meticulous notes about his meetings and briefings as national security adviser and then used a personal email account and messaging platform to share information classified as high as top secret with his family members. After sending one document, Bolton wrote in a message to his relatives, “None of which we talk about!!!” In response, one of his relatives wrote, “Shhhhh,” prosecutors said.

The two family members were not identified in court papers, but a person familiar with the case, who spoke on condition of anonymity to discuss nonpublic details, identified them as Bolton's wife and daughter.

A Bolton representative told the FBI in July 2021 that his email account had been hacked by operatives believed to be linked to the Iranian government but did not reveal he had shared classified information through the account or that the hackers now had possession of government secrets, according to the indictment.

Bolton's attorney, Abbe Lowell, said in a statement that the “underlying facts in this case were investigated and resolved years ago.”

He said the charges stem from portions of Bolton's personal diaries over his 45-year career in government and included unclassified information that was shared only with his immediate family and was known to the FBI as far back as 2021.

“Like many public officials throughout history,” Lowell said, “Bolton kept diaries — that is not a crime.” He said Bolton “did not unlawfully share or store any information.”

Justice Department has long history of classified documents cases

The Justice Department has a history of investigations into the mishandling of classified information, including by public officials. The outcomes of those investigations have turned in part on whether officials developed evidence of willful mishandling or other crimes such as obstruction.

Trump, for instance, was charged not only with hoarding classified documents at his Mar-a-Lago estate but also with obstructing government efforts to get them back. The case was dismissed after he took office.

Prosecutors in a separate investigation found evidence that President Joe Biden had willfully retained classified documents but opted against charges in part because they thought Biden might come across to a jury as “sympathetic, well-meaning, elderly man with a poor memory.”

Another high-profile investigation concerned 2016 Democratic presidential nominee Hillary Clinton, who was spared charges after then-FBI Director James Comey said investigators did not determine that she intended to break the law when she sent emails with classified information on a private email server while serving as Secretary of State.

One investigation that may carry parallels to the Bolton case is the prosecution of former CIA Director David Petraeus, who in 2015 admitted to sharing classified information with his biographer. He was sentenced to probation following a plea agreement with the Justice Department.