Lieutenant General (Ret.) and 25th Assistant to the President for National Security Affairs.

H.R. McMaster is the Fouad and Michelle Ajami Senior Fellow at the Hoover Institution, Stanford University. He is also the Bernard and Susan Liautaud Fellow at the Freeman Spogli Institute and lecturer at Stanford University's Graduate School of Business.

Upon graduation from the US Military Academy in 1984, McMaster served as a commissioned officer in the US Army for thirty-four years. He retired as a lieutenant general in June 2018 after serving as the twenty-fifth Assistant to the US President for National Security Affairs. From 2014 to 2017, McMaster designed the future army as the director of the Army Capabilities Integration Center. As commanding general of the Maneuver Center of Excellence at Fort Benning, he oversaw training, education, and modernization for the Army's infantry, armor, and cavalry force.

He has commanded organizations in wartime including the Combined Joint Inter-Agency Task Force—Shafafiyat in Kabul, Afghanistan, from 2010 to 2012; the Third Armored Cavalry Regiment in Iraq from 2005 to 2006; and Eagle Troop, Second Armored Cavalry Regiment in Operation Desert Storm from 1990 to 1991. McMaster was a Hoover National Security Affairs Fellow from 2002-2003.

McMaster holds a PhD in military history from the University of North Carolina at Chapel Hill. He was an assistant professor of history at the US Military Academy. He is author of the bestselling books Dereliction of Duty: Lyndon Johnson, Robert McNamara, the Joint Chiefs of Staff and the Lies that Led to Vietnam; Battlegrounds: The Fight to Defend the Free World; and At War with Ourselves: My Tour of Duty in the Trump White House. His many essays, articles, and book reviews on leadership, history, and the future of warfare have appeared in The Atlantic, Foreign Affairs, Foreign Policy, National Review, the Wall Street Journal, the Washington Post, The Free Press, the New York Times, and The Economist.

McMaster is the host of Today's Battlegrounds and is a regular on GoodFellows, both produced by the Hoover Institution. He is a Distinguished University Fellow at Arizona State University.