Al Qaeda (AQ) has evolved into a significantly different terrorist organization than the one that perpetrated the September 11, 2001, attacks. At the time, Al Qaeda was composed mostly of a core cadre of veterans of the Afghan insurgency against the Soviet Union, with a centralized leadership structure made up mostly of Egyptians. Most of the organization's plots either emanated from the top or were approved by the leadership. Some analysts describe pre-9/11 Al Qaeda as akin to a corporation, with Osama Bin Laden acting as an agile chief executive officer issuing orders and soliciting ideas from subordinates. Some would argue that the Al Qaeda of that period no longer exists. Out of necessity, due to pressures from the security community, in the ensuing years it has transformed into a diffuse global network and philosophical movement composed of dispersed nodes with varying degrees of independence. The core leadership, headed by Bin Laden and Ayman al-Zawahiri, is thought to live in the mountainous tribal belt of northwest Pakistan bordering Afghanistan, where it continues to train operatives, recruit, and disseminate propaganda. But Al Qaeda franchises or affiliated groups active in countries such as Yemen and Somalia now represent critical power centers in ...