McMaster's appointment comes after Lt Gen Michael Flynn, who formerly occupied the position, was fired.

Flynn stepped down after misleading Vice President Mike Pence over his conversations with Russia's ambassador to the US.

The new appointee, a lieutenant general with the US Army, served in Iraq and Afghanistan, where he worked on a government anti-corruption drive.

Trump's first choice, retired Vice Admiral Robert Harward, had turned down the offer giving "personal reasons."

The US President announced the appointment at his Mar-a-Lago estate in Florida.

He called President McMaster "a man of tremendous talent and tremendous experience".

"He is highly respected by everybody in the military," he said.

According to BBC, Keith Kellogg, who took over as acting national security adviser after Flynn's resignation, will now serve as the National Security Council chief of staff.