It’s hard not to see shades of Saigon in the frenetic evacuation of Kabul last month — and wonder why U.S. leaders seem not to have learned from bungled foreign wars and nation-building efforts. In this second part of a series reflecting on the debacle in Afghanistan, Will and Siva speak with two historians of the post-Vietnam era. They shed light on the grandiose and self-interested visions America has tried to realize abroad and ask what hope there may be for a future of soft power and humanitarian goals.