President Obama is assembling a national security team designed for an era of downsized but enduring conflict, a team that will be asked to preside over the return of exhausted American troops and wield power through the targeted use of sanctions, Special Operations forces and drone strikes.

Obama's nominations of former senator Chuck Hagel as defense secretary and White House counterterrorism adviser John O. Brennan as CIA director signal second-term course adjustments at institutions that have been dominated by their lethal assignments during more than a decade of war.