Former United States National Security Adviser John Bolton has pleaded not guilty to federal charges over his handling of classified information.On Friday, Bolton surrendered to authorities at the federal courthouse in Greenbelt, Maryland, where he also delivered his plea.Recommended Stories list of 3 itemsend of listHe faces eight counts of transmitting national defence information and 10 counts of unlawfully retaining such information, each with the potential for 10 years in prison. If found guilty, he could spend the rest of his life in prison.Bolton has served under four Republican presidents: He was an assistant attorney general under Ronald Reagan, a diplomat under George HW Bush, an ambassador to the United Nations under George W Bush and a national security adviser for Donald Trump.But it is his relationship with Trump that has raised concerns that his prosecution could be politically motivated.Questions of retaliationBolton’s indictment is the third in a series of charges unveiled against prominent Trump critics since the president replaced the US attorney for the Eastern District of Virginia with one of his personal lawyers, Lindsey Halligan.Since she was sworn in on September 22, Halligan has pursued criminal indictments against James Comey, a former director of the Federal Bureau of Investigation (FBI), and Letitia James, New York state’s attorney general.In all three cases, Trump has a long and public history of acrimony with the defendants.Comey, for example, led the FBI during its in …