President Donald Trump has named Lt Gen Herbert Raymond "HR" McMaster as the new national security adviser, following the sudden ousting of Lt Gen Michael Flynn after contact made with Russian officials prior to inauguration.
Mr Trump made the announcement from his West Palm Beach resort and de facto Camp David, Mar-a-Lago. He said Mr McMaster is "a man of tremendous talent and tremendous experience".
Lt Gen Keith Kellogg had served as acting national security adviser, and will now serve as the chief of staff of the National Security Council.
The appointments follows a tumultuous end to the Trump administration's first month in office. It included the blockage of Mr Trump's controversial executive order to ban travel from seven Muslim-majority countries by a federal court, Mr Flynn's forced resignation, and the withdrawal of Labour Secretary pick Andy Puzder after decades-old domestic violence allegations came to light.
The selection of Mr McMaster, 54, has come as a surprise to some, as he is known for pushing back against authority. It calls into question how well he will work with a president who values loyalty to a fault and immediately attempts to discredit any criticism.
However, Mr McMaster – an active three-star general who had no choice but to say "yes" to the President – remains a well-respected military strategist.
The new national security adviser is a graduate of West Point and earned a PhD in US history from the University of North Carolina at Chapel Hill. He rose to prominence during the first Gulf War, where he was awarded a Silver Star, as he commanded the US 2nd Amy Cvalry Regiment involved in one of the biggest tank battles since World War II.
In 1997, he wrote Dereliction of Duty, a book that took a critical view of the US' handling of the Vietnam War.
