John Bolton, Donald Trump's former national security adviser, has pleaded not guilty to charges of mishandling classified information.

The 18 charges stem from allegations he shared or retained sensitive materials, including some characterized as top secret. He entered the plea after surrendering to authorities at a federal court hearing on Friday.

Bolton served during Trump's first administration but parted with the White House contentiously and has become one of the president's most vocal public critics.

The indictment makes Bolton, 76, the third of the US president's political opponents to face charges in recent weeks. Bolton has stated he would defend his lawful conduct.

Bolton, wearing a dark blue suit and maroon tie, did not speak with reporters as he arrived at the courthouse in Greenbelt, Maryland. Not guilty, your honor, Bolton said in court. He was released on his own recognizance, with a hearing in the case scheduled for 21 November.

Prosecutors have accused Bolton of using personal messaging apps and email to illegally transmit sensitive information. These documents revealed intelligence about future attacks, foreign adversaries, and foreign-policy relations, prosecutors wrote.

Bolton has proclaimed that he has become the latest target in a political weaponization of the Justice Department, aimed at those Trump perceives as enemies. The indictment claims Bolton shared diary-like entries with unnamed individuals and used his personal email for sensitive communications, with investigators highlighting a hacking incident purportedly linked to Iranian actors that compromised his accounts.

Bolton's attorney, Abbe Lowell, defended him by saying, Like many public officials throughout history, Ambassador Bolton kept diaries – that is not a crime, asserting that the records were unclassified and known to the FBI since 2021.

An indictment is a formal accusation issued by a grand jury, tasked with reviewing evidence before proceeding with a case. Bolton has faced scrutiny regarding his handling of classified information since attempting to release a tell-all book about his time during the Trump administration.

The Justice Department previously attempted to block the book due to potential classified content, although a federal judge ruled against them while rebuking Bolton for jeopardizing national security. While investigations continued into the Biden administration, they did not lead to charges until now.

Trump has frequently criticized Bolton on social media and in public, previously accusing him of illegally releasing classified information in his memoir, The Room Where it Happened. Following Bolton's indictment, he joins figures like former FBI Director James Comey and New York Attorney General Letitia James in facing criminal charges under Trump’s Justice Department.