Barack Obama has named the former Republican senator Chuck Hagel as the next US defence secretary.

"For his independence and commitment to consensus he's earned the respect of national security and military leaders, Republicans and Democrats, including me. In the senate, I came to admire his courage and his judgement, his willingness to speak his mind, even if it wasn't popular, even if it defied the conventional wisdom. And that's exactly the spirit I want on my national security team," said the president.

"I'd take the president's word that he likes and trusts former Senator Hagel, got to know him in the Senate, likes and trusts his position and his candour on a range of issues. But I think the calculus to go ahead and in the way that they are going ahead is that Senator Hagel for all of the courageous positions he's taken on Iran, on Israel, Hamas, lots of issues, that he will assure his fellow senators that those are positions that he held as a senator and they really will not have very much to do with his position as secretary [of] defence."

- Hillary Mann Leverett, a former US state department official

But the nomination still has to be approved by the senate and that is far from a formality.

Many Republicans have criticised the nomination, saying Hagel is too soft on Iran and not soft enough on Israel. And it has also drawn criticism from some Democrats too, who want one of their own in the post.

Obama also named longtime Central Intelligence Agency (CIA) staffer John Brennan to head the agency.

But why is Hagel's nomination so controversial?

Chuck Hagel has been criticised by Republicans for being "outside mainstream thinking on most foreign policy issues".

So where does he stand?

Hagel initially supported the US-led war in Iraq, but later sharply criticised how that war was managed.

As a senator, he called unilateral sanctions on Iran "counter-productive". But he has supported some sanctions and also endorsed labeling Iran a state sponsor of terrorism.

Hagel's support for Israel has come under scrutiny.

"It is a controversial nomination and in a lot of ways, a curious one .... Any time managing the Pentagon is a very difficult job to do. It is going to be particularly difficult over the next four years because of the cuts .... Chuck Hagel has never managed a large organisation, he's never managed anything larger than his senate office."

- Clifford May, a national security analyst

Many Republicans point to comments he made in 2008, when he said "the Jewish lobby intimidates a lot of people up here". On the flip side, he has also voted in favour of billions of dollars in military aid to Israel.

After the 9/11 attacks the US government began monitoring some Americans -  without their knowledge. As a member of the senate's intelligence committee, Hagel defended the government's actions, saying it struck a "delicate, but effective balance".

Hagel supported US involvement in a NATO force in Kosovo - during that country's war in 1999.

Inside Story Americas, with presenter Kimberly Halkett, discusses the new appointments with guests: Larry Korb, a former US assistant secretary of defence and a senior fellow at the Center for American Progress; Clifford May, a national security analyst and president of the Foundation for Defense of Democracies; and Hillary Mann Leverett, a former US state department official and also co-author of a new book: Going to Tehran: Why the United States Must Come to Terms with the Islamic Republic.

"How can we preach to other countries that you can't have nuclear weapons but we can and our allies can. There's no credibility, there's no logic to that argument."

Chuck Hagel, the nominated US defence secretary

Source: Al Jazeera