The National Security Advisor post, vacated by Mike Flynn’s resignation last week, has been filled with Trump’s announcement of Lt. Gen H.R. McMaster. McMaster recently was the head of the Army Capabilities Integration center which is a military think tank. McMaster will remain on active duty while serving as National Security Advisor. McMaster served in both Iraq wars and was the author of the novel “Dereliction of Duty” published in 1997 about the Vietnam War.