John Bolton, Donald Trump's former national security adviser, has arrived at a federal court to surrender to authorities on charges of mishandling classified information. The 18 charges stem from allegations he shared or retained sensitive materials, including some characterized as top secret. 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 said he would defend his 'lawful conduct'. On Friday, Bolton did not respond to shouted questions from reporters as he entered the courthouse in Greenbelt, Maryland, to surrender to authorities. He is expected to make an initial appearance before a judge and may have to stop at the US Marshals office for 'possible' fingerprinting and a booking photo. Prosecutors have accused Bolton of using personal messaging apps and email to illegally transmit sensitive information. Bolton added he had 'become the latest target in weaponizing the Justice Department to charge those he [Trump] deems to be his enemies with charges that were declined before or distort the facts.' The indictment also states that between 2019 and 2021, Bolton was the target of a hacking attack from a 'cyber actor believed to be associated with the Islamic Republic of Iran' that gained access to his account, exposing classified materials. The Justice Department continues to scrutinize Bolton's handling of classified information following the controversial publication of his book about his time in the Trump administration.