Afghanistan, a landlocked country in Central Asia, has improbably been at the center of international geopolitics for four decades. After the Soviet Union invaded in 1980, Afghanistan descended into an unending conflict that featured at various points most of the world's major powers. In the mid-1990s, the country entered a new phase, when the Taliban took power and imposed order based on a harsh, repressive version of Islamic law. Infamously, the...