Military tactician will replace Flynn

US President Donald Trump on Monday named Lieutenant General Herbert Raymond McMaster as his new national security adviser, choosing a military officer known for speaking his mind and challenging his superiors.

McMaster is a highly regarded military tactician and strategic thinker, but his selection surprised some observers who wondered how the officer, whose Army career stalled at times for his questioning of authority, would deal with a White House that has not welcomed criticism.

"He is highly respected by everybody in the military and we're very honored to have him," Trump told reporters in West Palm Beach where he spent the weekend.

"He's a man of tremendous talent and tremendous experience."

One subject on which Trump and McMaster could soon differ is Russia.

McMaster shares the consensus view among the US national security establishment that Russia is a threat to the US. While the man whom McMaster is replacing, retired Lieutenant General Michael Flynn, appeared to view it more as a potential geopolitical partner.

Flynn was fired as national security adviser on Feb 13 after reports emerged he had misled Vice-President Mike Pence about speaking to Russia's ambassador to the US about US sanctions before Trump's inauguration.

Senator John McCain, chairman of the Senate Armed Services Committee, praised McMaster as an "outstanding" choice.

Trump also named Keith Kellogg, a retired US Army general who has been serving as the acting national security adviser, as chief of staff to the National Security Council.

John Bolton, a former US ambassador to the UN, will serve the administration in another capacity, Trump said.

Kellogg and Bolton were among those in contention as Trump spent the long Presidents Day weekend considering his options for replacing Flynn. His first choice, retired Vice Admiral Robert Harward, turned down the job last week.

McMaster, 54, is a West Point graduate with a PhD in US history from the University of North Carolina at Chapel Hill.

He was listed as one of Time magazine's 100 most influential people in 2014, partly because of his willingness to buck the system.