Profile: Chuck Hagel
US Defence Secretary Chuck Hagel is a straight-talking maverick, a former Nebraska Republican senator and a decorated war veteran.
The 66-year-old was eventually appointed to replace Leon Panetta, after a bitter fight in Congress.
Mr Hagel brings military experience to the job, having served as an infantry squad leader in the Vietnam war, where he was awarded two Purple Hearts, one for saving his brother's life.
He still has some shrapnel fragments lodged in his chest.
The horrors of war are said to have shaped his view of military action as a last resort, to be used only after all diplomatic options have been exhausted.Deprived childhood
Born in North Platte, Nebraska, Mr Hagel grew up in a poor family, and began working odd jobs from the age of nine to help put food on the table.
Chuck Hagel in his own words
- On Iran sanctions: Isolating nations is risky...It turns them inward, and makes their citizens susceptible to the most demagogic fear mongering.
- On a nuclear Iran: These governments, however hostile they may be toward us, have some appreciation of the horrific results of a nuclear war and the consequences they would suffer.
- On the United Nations: [The] only international organization that can help bring the consensus that is indispensable in finding solutions and resolving crises
- On the Pentagon: Bloated budgets and lack of effective oversight and review are symptoms of deeper, structural inadequacy in our military posture
From Chuck Hagel's 2008 book, America: Our Next Chapter.
Upon returning from Vietnam, he took various jobs, including as a radio reporter, before landing a post on the staff of a Nebraskan lawmaker in Congress.
After a stint at the Veterans Administration, he went on to make his fortune in the fledgling mobile phone industry.
Moving back to Nebraska, he was elected to the Senate in 1996 and again in 2002, where he rose to become chairman of a panel on the foreign relations committee.
Mr Hagel's strained relations with the Republican party leadership were seen as a reason for his decision not to pursue a White House run in 2008.
Some Republicans had never forgiven him for his strident criticism of George W Bush's administration during the Iraq war.
Though he voted for the resolution authorising the conflict, he went on to become a fierce critic, labelling the White House's handling of the military effort "beyond pitiful".
He had also called the planned 2006 troop surge "the most dangerous foreign policy blunder in this country since Vietnam, if it's carried out".
Mr Hagel was appointed as President Barack Obama's defence secretary in February 2013, following a nomination that was stalled in the Senate by an unprecedented filibuster.
His 58-41 confirmation was the narrowest ever vote margin for a Pentagon nominee.
Lawmakers on the right had voiced concern because Mr Hagel had openly challenged the idea of a US- or Israeli-led military strike against Iran. His support for including Iran in peace talks on Afghanistan had raised eyebrows, too.
Mr Hagel was also lambasted for saying in a 2008 book written by a former state department official that the "Jewish lobby" intimidated lawmakers in Washington. He apologised for that remark during his Pentagon confirmation hearing.
On the left, some had also criticised his remarks about James Hormel, the first openly gay US ambassador, in 1998.
Mr Hagel had opposed the envoy's appointment to Luxembourg, calling him "aggressively" gay. He later expressed regret for that comment.