Ashton Carter has been confirmed by the Senate on the post of a chief of Penrtagon. Carter will be Obama's fourth defense secretary in six years, joining a line of succession that began with Robert Gates and included Leon Panetta and Hagel.
Carter will replace Chuck Hagel, the former Republican senator who had a rough relationship with Obama's insular group of national security advisers.
One of Carter's first tasks will be helping to win support for Obama's call to Congress for new authority to use force against the IS extremists. Republicans and Democrats have reacted negatively to Obama's draft proposal, criticizing both its limitations and vagueness.