President Barack Obama on Friday named Ashton Carter, a technocrat and academic with deep experience working in the Pentagon, to replace Chuck Hagel as US defense secretary.

President Barack Obama on Friday named Ashton Carter, a technocrat and academic with deep experience working in the Pentagon, to replace Chuck Hagel as US defense secretary.

Obama praised the 60-year-old former deputy defense secretary, saying that he would bring to the job "a unique blend of strategic perspective and technical know-how."

"All of which means on day one, he will hit the ground running," Obama said, making the announcement from the White House.

Carter said he had accepted Obama's offer "because of the seriousness of the strategic challenges we face -- but also the bright opportunities that exist for America if we can come together to grab hold of them."