"The bonds of community, of tribe, are a very, very particular thing." - Sebastian Junger Courtesy Of TED hide caption

itoggle caption Courtesy Of TED

Afghanistan's Chief Executive Officer Abdullah Abdullah (left) stands with President Ashraf Ghani, Vice President Joe Bidden, Defense Secretary Ash Carter and Maj. Gen. Jeffrey Buchanan at a wreath-laying ceremony at the Tomb of the Unknowns on Tuesday. Andrew Harnik/AP hide caption

itoggle caption Andrew Harnik/AP

Sgt. Bowe Bergdahl prepares to be interviewed by Army investigators in August 2014. Eugene R. Fidell/AP hide caption

itoggle caption Eugene R. Fidell/AP

Afghan President Ashraf Ghani at the Blair House in Washington, D.C. Ghani will be meeting with President Obama this week. Emily Jan/NPR hide caption

itoggle caption Emily Jan/NPR