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 characterised 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 Trump's political opponents to face charges in recent weeks. He has vowed to defend his lawful conduct.

Bolton, dressed in a dark blue suit and maroon tie, stated Not guilty, your honor, during his court appearance. He was released on his own recognisance, and a hearing has been scheduled for November 21. Prosecutors allege he transmitted sensitive information through personal messaging applications and email, detailing intelligence on future attacks and foreign adversaries.

Despite the serious nature of the charges, Bolton maintains that he acted legally and plans to contest the accusations. His attorney, Abbe Lowell, argues that the records in question were unclassified and previously known to the FBI.

The charges against Bolton come in the wake of increasing scrutiny over his handling of classified information, particularly after the release of his book detailing his time in the Trump administration, which had drawn allegations of including classified content. The Justice Department had previously attempted to block its release, but a federal judge ultimately ruled against the government's efforts, though criticized Bolton for jeopardizing national security.

This indictment follows similar actions taken against other political opponents of Trump, raising questions about the motivations behind these legal proceedings as Bolton asserts that he is being targeted by a politicized Justice Department.