President Barack Obama says Chuck Hagel, his choice as the new secretary of defense, is "the leader that our troops deserve."

Obama formally announced his choice of Hagel in the White House East Room on Monday even as critics questioned the pick over issues including Hagel's views on Israel and Iran.

Facing a potentially tough fight to get Hagel confirmed by the Senate, Obama praised the former Nebraska senator's independence and bipartisan approach, and said that Hagel, a Vietnam veteran, understands war is not an abstraction.

Hagel, a moderate Republican, has the support of some of his former Senate colleagues but is drawing opposition from others who accuse him of being soft on Iran and insufficiently supportive of Israel.