How did Afghanistan fall to the Taliban after 20 years of effort by the United States and its allies?  SSI Live host Dr. John R. Deni invited his SSI colleagues Dr. Chris Mason to address the end of America’s longest war and to help shed light on the key reasons for why Afghanistan fell.  Dr. Mason drew on his long experience working in and studying Afghanistan, as well as his book The Strategic Lessons Unlearned from Vietnam, Iraq, and Afghanistan.