The most stunning attack ever made on the United States took place on the morning of September 11, 2001. Nineteen members of the al-Qaida terrorist network hijacked four commercial airliners, crashing two into the twin towers of the World Trade Center in New York City and one into the Pentagon in Washington. The fourth plane crashed in rural Pennsylvania. Thus began a new global conflict, a "war on terror," that had profound effects upon American society, culture, and role in world affairs.

The Attack

The plot was concocted by a veteran jihadist named Khalid Sheikh Mohammed, a Kuwaiti from a religious family who had attended college in the United States, which he hated violently. He had helped his nephew plan the 1993 attack on the World Trade Center. In 1996 he went to Afghanistan to join forces with al-Qaida, headed by Osama bin Laden. It approved his scheme in 1999 and supplied guidance...