Directorate S is a covert department within Pakistan’s Inter-Services Intelligence (ISI) agency. It is dedicated to supporting Islamist radicals, Kashmiri separatists and the Afghan Taliban. ISI has always been led by a three-star army general, answerable to the chief of the general staff. For much of the period covered by Steve Coll’s book, General Ashfaq Kayani loomed large, serving as director-general of ISI from 2004 to 2007, before becoming chief of army staff. He figures prominently in Coll’s account, often veiled by a cloud of cigarette smoke.

To many outsiders, ISI looks very much like a rogue agency. For instance, it nurtured the Lashkar-e-Taiba group, which perpetrated the 2008 terrorist massacres in Mumbai. ISI has also been closely involved in the chaotic affairs of Afghanistan, something that has been easy to achieve since ethnic Pashtuns