In order to prevent terrorism, one has to understand terrorists. There is no better way to do so than to understand their thinking and feelings — in essence getting a peek into their minds. Given the unreliability of memory, one of the best windows into an individual’s mind is a diary written at the time of events. The publication of Zain Abidin Mohammed Husain Abu Zubaydah’s diary is a critical development in the study of a terrorist movement. This may help answer some of the mysteries of why and how people become terrorists.

The diary, started in 1990, shows a 19-year-old man, somewhat estranged from his Palestinian family in Saudi Arabia, who had gone to India to study computers the year before. As a Palestinian refugee, he was discriminated against in Saudi Arabia, and this area of study was closed to him there. In India he felt betrayed by his friends, homesick and somewhat despondent. He sought refuge in religion and, together with a friend, decided to go for military training in Afghanistan in January 1991. Arriving at the Khaldan paramilitary training camp, he felt at home with other young men like himself, men wanting to become Muslim soldiers, mujahedeen, to fight the communist Afghan government. He returned to India to pack up, went back to Khaldan for a few months’ training and then, with his class and trainer, went to the front near the city of Gardez in the fall of 1991. He was part of the Arab contingent — young Arab men who arrived from around the world, primarily the Middle East and North Africa, to help Afghan resistance fighters against the communist-supported government of President Mohammad Najibullah.

In December 1991, Abu Zubaydah was wounded by mortar shrapnel that penetrated his skull. He was incapacitated for about eight months. During his recovery, the Najibullah government fell, and the various Afghan mujahedeen factions turned on one another, with each warlord fighting his rivals. The Arab foreigners were in a quandary. Should they stay and train other Muslims to free themselves from despotic regimes? Should they go to new lands of jihad — Kashmir, Algeria, Bosnia, the Philippines? In December 1992, Abu Zubaydah accepted an invitation to become a trainer to Tajiks at Al Faruq, a jihadi camp near Kandahar funded by Osama bin Laden.

Abu Zubaydah’s training took the better part of a year, during which he gradually adopted the social identity of international jihadis. He thought about joining Al-Qaeda but did not. Instead, by 1994, mostly because of his seniority and ability to help newcomers, he became the emir of the House of Martyrs, a welcoming center in Peshawar, Pakistan, for Muslims going to Afghanistan for training. He established a close link between this house and the Khaldan camp, whose emir was Ibn al-Sheikh al-Libi.

By the summer of 1994, under pressure from the U.S., Saudi Arabia and Egypt, Pakistani authorities were cracking down on the Afghanistan Arabs. By this time, Abu Zubaydah had naturally identified with the jihadis in Pakistan and developed an us-versus-them view of the world consistent with his belonging to this group. He was arrested and beaten by the Pakistanis in the summer of 1995 and released a few months later through the intercession of friends.