U.S. administration officials say President Barack Obama has chosen Ashton Carter as his next defense secretary.
A formal announcement on the nomination of Carter, a 60-year-old physicist and former deputy defense secretary, is expected in the coming days.
Carter would replace Chuck Hagel, who resigned last week under pressure from Obama after less than two years in the job.
Carter, the Pentagon's chief weapons buyer from 2009-11, helped speed up the production and shipment of weaponry and armored vehicles to protect American troops from roadside bombs in Iraq and Afghanistan.
He has no uniformed military experience.
The next defense chief -- Obama's fourth -- will face challenges from the rise of Islamic State militants in Iraq and Syria to Russian aggression in Ukraine, global efforts to contain Iran's influence, and an increasingly assertive China.