US President Donald Trump is interviewing at least four potential candidates to serve as his new national security adviser. <br/><br/>White House spokesman Sean Spicer says that Trump will interview his acting adviser, retired Army Lt Gen Keith Kellogg; a former US ambassador to the United Nations, John Bolton; Army Lt Gen H R McMaster; and the superintendent of the US Military Academy at West Point, Lt Gen Robert Caslen.<br/><br/>Trump is working to replace ousted national security adviser Michael Flynn after hisfirst choice retired Vice Admiral Robert Harward turned down the offer.<br/><br/>