Ashton Carter, who faces Senate confirmation, was deputy secretary from 2011 to 2013.
President Obama will announce his choice of former Pentagon official Ash Carter to be his next secretary of defense on Friday, the White House said.
Ashton Carter may be President Obama's top defense secretary nominee among other candidates.
Eamon Javers, Washington Correspondent for CNBC said U.S Secretary of Defense Chuck Hagel's resignation may have appeared a "surprise", but President Barack Obama had known about this situation for a few months.
Defense Secretary Chuck Hagel is stepping down under pressure, the first Cabinet-level casualty of the November elections.
CNBC's Eamon Javers provides insight to reports saying Defense Secretary Chuck Hagel was forced to resign and is not stepping down as President Obama indicated.
U.S. secretary of Defence, Chuck Hagel says it's been "the greatest privilege of my life" to lead the defence department.
President Obama announces the departure of Secretary of Defense Chuck Hagel. Obama says Hagel will stay on until a successor is confirmed.
U.S. President Barack Obama gives his thoughts on the U.S.'s Secretary of Defense Chuck Hagel's resignation, saying that he's "grateful" that Chuck Hagel will stay on until a successor has been found.
Although the US spent $7.6 billion to eradicate poppy in Afghanistan, cultivation of the opium source is at an all time high.
Proposed military budget cuts proposed by the Pentagon last week may be far from what Congress finally agrees on.
President Obama is expected to release his full year 2015 budget on Tuesday. CNBC's Jane Wells reports defense stocks were up on a down market day today.
Americans and their elected officials continue to resist cuts to almost any specific program, big or small.
CNBC's Jane Wells reports that the Defense Department plans to request $496 billion for its base budget in 2015.
Defense Secretary Chuck Hagel is speaking at the Pentagon on defense budget cuts. CNBC's Jane Wells reports the defense department is requesting $496 billion this fiscal year.
CNBC's John Harwood is monitoring Defense Secretary Chuck Hagel's remarks on cuts to the defense industry.
Cai Von Rumohr of Cowen and Co. discusses the likelihood Congress will support Defense Secretary Chuck Hagel's proposed defense cuts.
Defense Secretary Chuck Hagel is speaking at the Pentagon on defense budget cuts. CNBC's Jane Wells reports Hagel is hoping Congress will support another round of base closings.
The U.S. government plans to shrink the Army in a new spending proposal. It would be the smallest force since before the Second World War.
Secretary of Defense Chuck Hagel has pledged to cut the Army by 80,000, but a new study by suggests that Hagel could cut more while doing no harm.
Oshkosh has won a contract to build 17,000 light tactical vehicles to replace the aging Humvees used by the Army.
A Canadian company has clinched a patent for a 12.4 mile-high "space elevator" that could launch astronauts and tourists into orbit.
Ukraine is edging closer to a return to full civil war following recent attacks on Kiev-controlled areas that have violated the ceasefire agreement.