The 18 charges stem from allegations he shared or retained sensitive materials, including some characterised 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 US Marshals office for "possible" fingerprinting and booking photo, CBS News, the BBC's partner in the US, reported. 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. Responding to the charges, Bolton said he would defend his "lawful conduct". (BBC)