Washington (AP) - Following the expulsion of National Security Advisor John Bolton, US President Donald Trump has named the names of five possible successors. He cited hostage special envoy Robert O'Brien, former National Security Advisor Rick Waddell, director of the Nuclear Safety Agency, Lisa Gordon-Hagerty, ex-chief of staff Fred Fleitz, and National Security Advisor Mike Pence, Keith Kellogg , However, other candidates are also considered, it is said from the White House.