Soon after turning eighteen, Hazmi packed a duffel bag and left for Afghanistan to learn the art of warfare. But by 1993 the war against the Soviet occupiers was long over and Osama bin Laden had returned to his contracting business in Sudan. Undeterred, Hazmi called his family from Peshawar, Pakistan, near the Afghan border, and told them he was going to fight in Chechnya. Very concerned, Muhammad al-Hazmi went to Peshawar to bring his son home. "I went to Peshawar," he recalled. "I found him there. He said he was staying in Pakistan as a trader of frankincense and we returned home together. I asked him to help me in my commercial ventures, including shops and hotels." Speaking of his sons, he added, "In fact, I planned to open branches for them and to find brides for them. But they did not stay for long."

Returning to Mecca with his father, Hazmi met with a key al-Qaeda member and in 1996, bubbling with enthusiasm, convinced Mihdhar to join him in a new war, this one in Bosnia defending fellow Muslims from attacks by the Serbs.

What drove Mihdhar, Hazmi, and thousands of others was a burning need to defend Muslim lands from the West, which had a long history, as they saw it, of invading and occupying their territory, killing and humiliating their families, and supporting their corrupt rulers. The victory in Afghanistan over the Soviets, a superpower, was their first real win and gave many Muslims across the region a sense of unity, fueling an ideology that viewed their separate countries as a single Muslim nation — what they called the "ulema." An occupation or invasion of one Muslim state was therefore an aggression against all Muslim states.

Now with the taste of victory over Russia still sweet in their mouths, adrenaline still pumping through their veins, and a new sense of Muslim nationalism, many were no longer willing to sit and wait for the next encroachment on their lands. The West had long waged war on Islam, they believed; now it was Islam's time to defend itself and fight back. The time had come to go on the offensive.

On August 23, 1996, Osama bin Laden issued his call to action: "My Muslim Brothers of the World," he said. "Your brothers in Palestine and in the land of the two Holy Places [Saudi Arabia] are calling upon your help and asking you to take part in fighting against the enemy — your enemy and their enemy — the Americans and the Israelis. They are asking you to do whatever you can, with your own means and ability, to expel the enemy, humiliated and defeated, out of the sanctities of Islam."

Turning his attention to the United States, he said, "[We] hold you responsible for all of the killings and evictions of the Muslims and the violation of the sanctities, carried out by your Zionist brothers [Israel] in Lebanon; you openly supplied them with arms and finance [during Israel's bloody Grapes of Wrath invasion]. More than 600,000 Iraqi children have died due to lack of food and medicine and as a result of the unjustifiable aggression [the sanctions] imposed on Iraq and its nation. The children of Iraq are our children. You, the U.S.A., together with the Saudi regime, are responsible for the shedding of the blood of these innocent children."

The charges resonated with Mihdhar and Hazmi, and in about 1997 Hazmi returned to Afghanistan, formally swore his loyalty to bin Laden, and fought against the Northern Alliance, possibly with his brother, Salem. Mihdhar followed, and swore his allegiance to the al-Qaeda leader in 1998. They would become the elite of al-Qaeda, among the first seventeen to join from the Arabian Peninsula. Bin Laden would call them "The Founders." Early on, the al-Qaeda leader had developed a special affection and trust — almost father-son at times — for Mihdhar. They shared a common heritage, both sets of ancestors having come from the remote, desolate Yemeni province of Hadramont.